MAY

"Amateur astronomers face a variety of perplexing limitations in their humble observing stations upon the Earth's surface," Scotty once lamented. He was referring not so much to the turbulence of our atmosphere (not to mention clouds), but to the fact that Northern Hemisphere observers cannot see deep into the southern sky. Scotty often remedied this situation by traveling southward. But he also liked to "graze the grass" visually from his homeland. In doing so, he discovered — to the surprise of many — that the great southern globular cluster Omega Centauri is not out of reach for observers at mid-northern latitudes. By discussing this seemingly impossible target in his column, Scotty introduced what would arguably become his most famous visual challenge. Of course, nothing beats seeing this globular from more southerly locales. Shortly before his death in 1993, Scotty traveled to the Winter Star Party (WSP) on Florida's Big Pine Key, which offers southern views to a declination of -65°. And it was at WSP that Scotty saw Omega Centauri for the first time through one of amateur astronomer Bob Summerfield's impressive Dobsonian reflectors. The eyepiece was so low to the ground that all Scotty had to do to enjoy the view was to stroll to the waterfront in the predawn hours and sit in a chair. There, within earshot of rustling palms and waves lapping gently on the shore, Scotty sat in silent contemplation, staring at this blazing wonder as if it were the key to all understanding. He looked for countless minutes, until a tear moistened his ^eye and misted the starlight. Scotty truly loved the heavens.

When the jet stream bulges southward, it allows Canadian air to pour across the United States and cover all but the far West with a stable mass of cold air. Amateur astronomers benefit with dark nights of crystalline transparency end better astronomical seeing. Under these conditions it is no problem viewing Nh-ntagnitude stars only 1° above the horizon. Globular cluster fans should wait that special evening to try for Omega (co) Centauri (Figure 5.1), the finest of globulars. The search must be done when the cluster is at its highest point in ^{e s}ky. On May evenings the cluster lies near the meridian. It culminates at the ^Sanie time as Spica; just look for the cluster 36° below the brilliant star.

Figure 5.1 Although the great globular cluster Omega Centauri is an easy naked-eye object for viewers in more southern latitudes, it is a challenge to observers at north temperate locales. The higher-power view at bottom shows millions of stars.

To the naked eye, Omega shines with the light of a 3.7-magnitude star (Figure 5.2); however, its image is rather soft, not crisp like that of a real star. The cluster covers about a Moon’s diameter of sky but does not appear that large to the eye. Ptolemy cataloged it as a star over 18 centuries ago, and Johann Bayer did the same in the early 1600s (hence the Greek-letter designation). In 1677, Edmond Halley was the first to record the object as a cluster. With moderate optical aid, the cluster is enthralling: an area more than half as broad as the Moon is thickly strewn with glittering stardust. And John Herschel gave a vivid description of Omega s appearance in his 18%-inch reflector in South Africa on March 3,1837: “All clearly resolved into stars ... this most glorious object fills the whole field with its most condensed part, and its stragglers extend % of a field beyond it either way." If^wewere located inside this cluster, we would see the night sky ablaze with many thousands of lst-magnitude stars, and it would be twilight all night long.

In theory, an observer in the Northern Hemisphere can see into southern dec-lions as far as the corresponding co-latitude (down to 90 minus the latitude of location). From geometry alone we can calculate that Omega Centauri "’mid visible from as far north as 42/’° north latitude. In practice that value is small, because atmospheric refraction at the horizon lifts starlight by Z°, so ^_ie»a might be viewed from 43°.The challenge is to see it through terribly dense _and contaminated air.

Figure 5.2 Despite its distance of 18,000 light-years, Omega Centauri can be seen with the naked eye as a 3.7-magnitude fuzzy "star."

Ordinarily horizon mists, smoke, and dust take a good 10° or 15° off this figure. But on those special nights when extinction is small and stars can be seen down to the horizon, Omega Centauri should theoretically be visible to amateurs living near New York City, Pittsburgh, Cincinnati, and San Francisco. If you live near the northern limit of visibility, try 65-mm binoculars from a high hilltop. The cluster "ill appear as a large patch of light, dimmed by atmospheric extinction.

Record telescopic sightings from the Northern Hemisphere give us a clue to the 'ask s difficulty. For instance, Harry Koken of Bird City, Kansas, bought a secondhand 6-inch objective and fabricated a telescope around it in the 1950s. At his *^a'itude (39° 45') Omega Centauri was indeed horizon-scratching. Yet Koken ^lnc>uded it in his list of the 10 greatest sights through that 6-inch. We can also trust , ’ D. Flynn’s sighting from near Pittsburgh, Pennsylvania (40.4° north). With a 10-^lnch reflector at 50x he found it an “unmistakable white haze, pretty large, not resolved but with a couple of stars seen on its borders." At latitude 41.8° in th_every northern reaches of California near Yreka. Russell Milton viewed Orrieg_abetween the trees on a distant hill. His homemade 8-inch f/4.7 reflector showed the cluster as "very bright, resembling a comet, with one or two of the bright_es. cluster members near the edge visible." It has also been seen from near th_eCalifornia/Oregon border.

Here in East Haddam, Connecticut. I have climbed a broad hill in a cow _pasture and with binoculars have seen the giant cluster passing between tree branches. I have yet to bring a telescope to this site, but it is unlikely the cluster could be resolved at such a low altitude. Years ago in Manhattan, Kansas. I had a visitor from New York who said he had never seen it, and, trusting to theory and my growing faith in Kansas skies, I offered to show him this cluster. Anil there it was in the binoculars, its lower edge just tangent to the top of the Flint Hills. In the 6 x 30s its immense size was obvious, and while it had lost about three magnitudes by extinction, the brighter stars came through, clearly making it look more like a bright galactic cluster than the globular it really is. The next night at the same time a 6-inch rich-field telescope showed clearly the glow of its thousands of unresolved stars. The apparent size of Omega Centauri depends not only on the size of your telescope but also on your reaction to seeing scattered light. It’s rather like the better-understood “cocktail-party effect” — the more sensitive you are to hearing, the more conversations you will overhear.

When I was in Campeche, Yucatan, I was far enough south to make a fair comparison between four great globular clusters. Omega Centauri has an appreciable diameter to the naked eye — not the 30' listed in some books, but certainly 15'. Seen in a 414-inch f/4.5 Tuthill Star Trap reflector, this cluster looked much the way M13 does with my 4-inch Clark refractor back in Connecticut. Although M13 was also visible to the naked eye, in binoculars it was a pale imitation of Omega Centauri. Also with binoculars, M13 seemed a shade brighter than M3 in Canes Venatici. However, the 18x Star Trap made the difference in brightness appear less obvious to me. Omega also surpassed M5 in Serpens, though both were riding high in a black-velvet sky. Certainly, if it were well placed in the northern sky. Omega Centauri would be as popular as the Orion Nebula.

Galaxy Visibility

Although Scotty enjoyed "rummaging" through Leo Minor's celestial closet of galaxies, he also found it a decent proving grounds for optics. For example, in his May 1951 Deep-Sky Wonders, he pondered the problem of galaxy visibility through various apertures. He suggested his readers train their telescopes on a gathering of three visually disparate galaxies in Leo Minor — NGC 3414, NGC 3504, and NGC 3486 — and report on the difficulty of seeing each one in various sized telescopes (including their finders). "Does the difference in brightness seem comparable to their listed difference in magnitude?" he asked. "How does magnification affect

visibility- Does the total light seem equivalent to that of a star of the same •b^el 'tilde!¹ Try expanding a star out of focus until it is the same diameter as the ^nl1!l' (that is, compare the object in focus with a star out of focus)." Scotty was ^^ving hi^s magic, prompting us to go out and give thought to the quandaries of the "^l ble universe. It is through such exercises that he helped us grow as observers.

May 1951, this column listed three galaxies in Leo Minor. NGC 3414 at mag-I " tude 12.2; NGC 3504 measured at 11.7; and NGC 3486 (Figure 5.3) showing a nitude 11-4- Observers were asked to report on the visibility of these objects under various apertures and powers. The several amateurs who collaborated _erely add evidence that the problem of nebular visibility is not a simple one. We re especially indebted to William Galbraith of Lemon Grove, California; James Corn of Phoenix, Arizona; and to Fred Grabenhorst of O’Fallon. Missouri.

The observers all agree that it requires more than three inches to see 11 th-magnitude objects. With a 12‘Z-inch instrument, Corn tried reduction masks until the visibility was nil. But on the effect of powers, they differ. With a 5-inch telescope Galbraith met “increasing difficulty” as he raised his magnification, whereas Corn found 3414 and 3504 as easy at 400x as at 80x. But Corn says that 3486 seemed to fade off with increasing powers; and all three were invisible at l,()00x. Grabenhorst was unable to see any of these galaxies with a 3-inch telescope.

The Arizona observer suggests that 3486 has "luminosity per unit area evidently much lower than the other two.” Galbraith, a variable-star observer, estimated the magnitudes differently from the catalogs: 3414.12.0; 3504.12.0; 3486,12.3.

From these and other reports it seems likely that brightness holds fairly steady as magnification increases until a certain point, after which it falls off very fast.

On an exceptionally clear night in January 1976,1 re-observed these galaxies with a 4-inch Clark refractor, 5-inch Moonwatch Apogee telescope, and a pair of 5-inch 20x binoculars (having the same optics as the Apogee telescope). In the refractor, the galaxies were easily visible. Even when it was stopped down to three inches, all of them were seen at 400x.but at 50x only NGC 3504 (the easternmost of the trio) could be detected. The 20x Apogee telescope failed to show any, but the binoculars steadily held NGC 3504. Lately, I have become increasingly aware that more can be seen with two eyes thar. with only one. (Microscopists have known this for centuries.) Therefore, my own experience has been about halfway between those of °m and Galbraith. The optical system may have a considerable effect. It might be •nteresting to compare Newtonian and Cassegrainian arrangements.

The visibility of galaxies raises some important practical observing problems. ^uPpose an observer whose eye is properly dark-adapted has a transparent, °onless sky. How large a telescope is needed to see some particular galaxy? The answer depends on the total magnitude of the object, its angular size, and its sur-^ce brightness. A closely related question is: If an amateur wishes to view a galaxy ^as distinctly as possible in a certain telescope, what magnification and what diam-^r °f field are best? What observing techniques can aid detection?

By observing these three visually disparate galaxies in Leo Minor — NGC 3414, NGC 3504, and NGC 3486 — amateurs can learn about the practical problems of observing galaxies. North is to the left. The streak across the lower right corner is a satellite trail.

carry NGC numbers were discovered with the large telescopes built by Lord Rosse in Ireland. Good luck!

The Dwarfs that Dwell in Leo

During a trip to California in 1980, Scotty learned of an interesting observation from Gerry Rattley, president of the San Jose Astronomical Association. He told Scotty that another West Coast observer, Lee McDonald, had been examining one of the Palomar Sky Survey plates (made with the 48-inch Schmidt telescope) when he found a very faint nebulosity in Leo just north of brilliant Regulus. "However," Scotty notes, "he expected the object to be beyond the reach visually of amateur-size telescopes." But one night Rattley and McDonald pointed a 17-inch altazimuth-mounted reflector (belonging to the San Francisco Sidewalk Astronomers) toward it. "Using powers of 50x and 100x, and by keeping Regulus just out of the field," Scotty continues, "both observers were able to see a faint glow without averted vision, filling more than half the field of view." These amateurs were looking at the dwarf spheroidal galaxy Leo I — an inconspicuous member of the Local Group of galaxies. This observation led Scotty, in April 1990, to ponder the incredible changes he had witnessed in amateur astronomy in his long career ^as an observer and columnist for Sky & Telescope.

As we begin the last decade of the 20th century, I'm flooded with the realization of how much astronomy has changed in my own lifetime and how ^rapidly it continues to change. In the 1930s I remember when the first photo-^lr*to space with detectors thousands of times more sophisticated than that crude Photometer of the 1930s.

r\._ has reappeared in a new dress, and there's growing belief that impacts h_aVcgreatly affected the course of life on Earth.

Nearly as impressive as the spacecraft missions to the planets has been the growth of amateur astronomy. During the 1920s articles in Scientific American got the telescope-making fad launched in North America, which greatly increased the number of amateur astronomers. This, in turn, made it economi-cally feasible to publish a magazine devoted to popularizing astronomy; it wasn't long before the forerunners of Sky & Telescope were rolling off the presses. These magazines provided a successful place for commercial telescope-makers to advertise. It was an upward spiral that continues to this day.

Amateurs work very differently now than they did only a few decades ago. For example, in the early years of deep-sky observing I would set up a small refractor near my home in Milwaukee’s Bay View. With a copy of Norton's Star Atlas in hand (the only deep-sky reference commonly available at that time), I would sweep the sky. Today’s beginners arc likely to have an 8-inch or larger telescope and access to detailed charts showing hordes of galaxies. Tirion’s Sky Atlas 2000.0 gave us 2,500 deep-sky objects. Uranometria 2000.0 plotted four times as

Figure 5.4 The 10th-magnitude Leo I dwarf galaxy would be an easy target for most amateur telescopes, if brilliant Regulus weren't so close; the star lies a mere '/° due south of the galaxy. many. And it’s easy to find reference material for others. Even the most skilled observers don't have to look too far to find information on difficult objects.

blot all the sky s challenges have to be found with sophisticated charts. Leo •ind its beacon Regulus, at magnitude 1.35, are well placed for viewing during evening hours in April. Only 20 stars shine brighter than Rcgulus. If you center that dazzling celestial jewel in your telescope and nudge the instrument just !4° due north, you come to the dwarf galaxy Leo I. It’s a member of the Local Group __ _a neighboring galaxy like the Magellanic Clouds, M31 in Andromeda, and one of my favorites, NGC 6822 in Sagittarius.

Leo I (Figure 5.4) shines with the total light of a lOth-magnitudc star. But because this glow’ is spread across a disk some 10' in diameter, the actual surface brightness is rather low. Nevertheless, were it not for glare from Rcgulus, Leo I would be an easy target for a 10-inch telescope. California amateurs Gerry Rattley and Lee McDonald managed to snare it with a 17-inch reflector. They used magnifications of 50x and lOOx and kept Regulus outside the field of view.

The 13th-magnitude galaxy IC 591 lies only %° west of Leo I. It’s about 1' in diameter. Although smaller and fainter than Leo I, IC 591 must be easier to see since it was found visually at the close of the 19th century and Leo I wasn’t discovered until 1950, when it was photographed with the 48-inch Schmidt telescope at Palomar Mountain.

Even more challenging would be dwarf galaxy Leo II (Figure 5.5). It too is a member of the Local Group. Leo II is slightly smaller than Leo I, and about 1J4

magnitudes fainter. I have not heard of any amateurs observing this system b_utjudging from the experiences of Gerry and Lee, I suspect it could be seen with 16-inch aperture.

Galaxy Hunting in Leo

Tirelessly observant, Scotty found that a quick glance at Wil Trion's Sky Atlas 2000.0 revealed some interesting facts about Leo. There are no planetary or diffuse nebulae plotted within the confines of the constellation, nor are there any globular or open star clusters. Observers will, however, find the celestial Lion a rich hunting ground for galaxies, with some 60 of them plotted in Sky Atlas 2000.0. Of course, the Millennium Star Atlas reveals many more. So when Northern-Hemisphere amateurs eagerly venture out under the springtime sky, they can enjoy many hours of galaxy viewing within the boundaries of this attractive constellation "Leo's prominent Sickle of bright stars is almost as easy to locate in the starry sky as the Big Dipper," Scotty said. "The beacon Regulus at the tip of the Sickle's handle helps guide the way, since there are only 20 brighter stars on all of heaven's vault. None of the Milky Way's silvery star dust is strewn across the constellation, and the naked-eye stars are rather few, so you do not easily get lost in Leo."

Spring is a time when the sky emerges from winter clouds. The Big Dipper is upside down above the pole, and if we follow the Pointer Stars to the south (rather than northward to Polaris), we can find Leo towering on the meridian.

To many of us, Leo symbolizes spring, just as Scorpius, Pegasus, and Orion do summer, fall, and winter. From Leo we can branch out to find all the other, lesser-known star patterns in the northern spring sky.

While the deep-sky objects of Leo might seem a little drab compared with the brilliant star clusters scattered across the winter Milky Way, there are some remarkable sights here for 8-inch and larger telescopes. Burnham’s Celestial Handbook lists over 70 deep-sky objects in Leo. All are galaxies from 9th to 13th magnitude. I wouldn’t even try to guess the number a 17-inch telescope could find. Within the boundaries of the constellation there is not one open or globular star cluster or planetary nebula suitable for amateur telescopes. This is interesting because Leo is the 12th largest constellation, covering just under 947 square degrees of sky.

About 10° east of Regulus lie M95,M96, and Ml05 — a trio of galaxies (Figure 5.6) all listed in modern versions of Messier’s catalog, but actually discovered by his fellow countryman Pierre Mechain.Thc latter was the more mathematically inclined and occasionally calculated the orbits of Messier’s comets. The two freely shared their deep-sky discoveries. As a case in point, two galaxies in the trio, M95 and M96, were first seen by Mechain on March 20,1781. He passed the information on to Messier, who located the pair four nights later. M96, at ntag-pjtude 9.2. is about half a magnitude brighter than M95. Both spirals (M95 is a barred spiral) are about 7 in diameter. They are not breathtaking (to say the least) and for users ot small telescopes, a good description is that they are bright enough to he seen. I have seen M96 as a pale white blur in instruments as small _aS g x 30 binoculars and a 1-inch, 40x refractor. Larger telescopes do not add much detail.

jvf95 is fainter but still within easy reach of a 4-inch. In fact, many observers consider M95 to be the more eye-catching galaxy, and some find M95 the more obvious of the pair. What do you think?

Both have bright central cores. Indeed, the nucleus of M95 can even be seen in large binoculars. Close scrutiny will reveal it to be a gently squared-olf circle. Long-exposure photographs made with large telescopes record two straight arms extending from the nucleus and a faint ring surrounding the nucleus. Some observers have also suggested that the central bar of M95 is visible in amateur telescopes. Can you confirm or deny the visibility of this feature?

Just to the northeast of the pair lies NGC 3379. which is number 105 in modern extended lists of Messier objects. It is an elliptical about 4 across and shines ^W|th the total light of a magnitude 9.3 star. It is located about 1° north-northeast °f M96. It too has a bright nucleus and a faint halo that fades into the background. It is curious that Mechain failed to notice Ml05 on the night he discovered M95 and M96.1 suspect he was comet hunting when he found the pair of

galaxies, and was probably making east-west sweeps parallel to the horizon wit), his refractor. Thus he could have easily missed the more northerly object.

M105 is visible in large binoculars. Two fainter galaxies lie just east of it. NQq 3384 (magnitude 10.0) is northwest of NGC 3389 (11.8). and together with MlOs they form a little triangle that is about 8' on a side; they were discovered by William Herschel. Interestingly, even though Ml05 is the prominent object William H. Smyth mentions the three under a heading for NGC 3384 in his 1844 Bedford Catalogue. Smyth further notes that he could not definitely see NGC 3389, though he suspected something at its approximate location. He was using a 5.9-inch refractor at his private observatory in England. There are at least half a dozen other 11th- and 12th-magnitude galaxies suitable for amateur telescopes spread across a few degrees of sky to the north of the Ml05 group.

At least five of Leo’s galaxies are large and bright enough to reveal internal detail in an 8-inch telescope. With a 17-inch you can spend half an evening on some of them. One of the most noteworthy is NGC 2903, a big 9th-magnitude spiral (Figure 5.7) about 4° southwest of Epsilon (e) Leonis, the star at the tip of the Sickle, and hangs like a misty jewel I/2⁰ south of Lambda (X) Leonis. NGC 2903 seems distinctly oval, but not as much as the catalog dimensions 11' x 4.6 suggest. At magnitude 9 it should be visible even in a good 2-inch finder. Long-exposure photographs show it as a single galaxy, but this object’s ownership of two NGC numbers, 2903 and 2905, is a reminder that early visual observers _oUght otherwise. In his Cycle of Celestial Objects, Smyth tells us that William linschel described it in 1784 as “a double nebula, each having a seeming nucle-with their apparent nebulosities running into each other." William’s son, John, d Smyth himself later observed duplicity. Smyth had some difficulty in making ^is out ^w**'¹ h*^s 6-inch refractor: “The upper or south part is better defined than lower: it requires, however, the closest attention and most patient watching, make it a bicentral object." It would be an interesting experiment to view NGC 2903 with a long-focus instrument at medium to high magnification, gradually reducing the aperture until the object becomes nearly invisible in the hope of inducing the "double" appearance. I myself have never been able to see such an appearance, despite experiments with various apertures. Has any reader of this column observed NGC 2903 as double?

I've always wondered why Charles Messier missed this galaxy, especially since he cataloged fainter ones in nearby Virgo. Ron Morales of Tucson, Arizona, found it “easy and impressive" as seen with an 8-inch reflector. California amateur Tokuo Nakamoto reports seeing a faint oval halo surrounding the "much brighter" center of NGC 2903 with his 14-inch reflector. Years ago in Kansas I viewed the galaxy with a 10-inch reflector at 120x. The arms were rather ill-defined, but several knots of material dotted the extensions around the core.

These knots are bright clouds of ionized hydrogen (called II II regions) similar to the Orion Nebula within our own galaxy. Photographers might try recording NGC 2903 with a series of exposures. Long ones should show the galaxy's arms in all their splendor, but shorter exposures may better reveal the knots and the nucleus. Astronomers have identified over 70 such glowing clouds within NGC 2903. In the 1960s I saw several of them with the 20-inch Clark refractor at

Tucked under the "triangle” of eastern Leo, yet passed over with slight attention by most handbooks, lie three galaxies so close together that some telescopes will show them in the same low-power field (Figure 5.8). The two brighter ones, M65 and M66, were discovered by Mechain. In his original catalog, Messier writes that the comet he discovered in 1773 must have passed through the field of these galaxies on the night of November 2, but that he missed them because of the comet's light. It wasn't until 1780 that Mechain found the two galaxies and relayed the discovery to Messier.

M65, the westernmost of the two brighter galaxies, is a lenticular object measuring 8' by 2', of visual magnitude 8.9 according to Johann Holetschek, while Owen Gingerich assigns 10. It is well worth inspecting, especially with the technique of averted vision, whereby its quite respectable dimensions will become apparent. The Webb Society handbook on galaxies mentions a dark lane just ^Wesl of M65’s nucleus, as seen with an 8!4-inch telescope. The lane is about 2!4' '°ⁿg- Visually, with my 10-inch reflector and a fine sky, this arm was only suspected, and probably not seen at all. Have others noted it?

galaxy but with a more regular and curdled appearance is M66 ts published dimensions are 8' by 2.5', and the visual magnitude is

8.6 (Holetschek) or 9 (Gingerich). M66 is more conspicuous than M65 and is usually visible in a 2-inch finder. It is interesting to compare these galaxies for brightness, to see if the difference of magnitude given above varies with the instrument, and whether it is the same for visual observations as for photographic. Generally, the visual magnitudes should be about a magnitude brighter than the photographic ones.

The skilled observer John Mallas called M65 “beautiful” in a 4-inch refractor, while M66 had a “mottled or clumpy appearance, reminiscent of the Orion Nebula” in the same telescope. This is due to numerous stellar condensations in the galaxy’s spiral arms.

Most photographs of M66 do not show this patchy appearance because the bright central region of the galaxy is overexposed. Compared with M65 in my 10-inch, M66 is hardly recognizable as a spiral, resembling a stray diffuse nebula, but photographs prove otherwise. It’s been my experience that many observers tend to overlook details in bright objects, perhaps because they think these easy-to-find things are for beginners. These same people will write me long letters about glimpsing a subtle brightening at the edge of some 13th-magnitude galaxy.

W. H. Smyth speaks of a third nebula close by, but this is a mistake copied from John Herschel. However, there is another spiral 1° west of the Messier paif-NGC 3593, which many people overlook because of the brighter galaxies just east of it. The galaxy is “bright” in a 16-inch. Look for an object about 3' long-

for an 8-inch, but on a particularly good night I caught a glimpse of it with my 4-inch Clark refractor and a 9-mm Nagler eyepiece. It might serve as an indicator _of seeing conditions. Indeed, these three galaxies, so conveniently located, can be used for tests of visual magnitude estimates.

For observers with access to large telescopes, there is a cluster of galaxies in Leo known as Abell 1367. It is one of the richest nearby galaxy clusters cataloged by George Abell. Near its center is NGC 3842, about T across and 13th magnitude. While this is the brightest of the group, nearly 30 other galaxies in a one-square-degree area have been seen with 16-inch telescopes. At 120x I can hold NGC 3842 steadily with the Clark. A good chart of this cluster is in Vol. 5 of the Webb Society Deep-Sky Observer’s Handbook.

Those who enjoy searching for difficult objects will probably find NGC 3588 to their liking. This faint (perhaps 15th-magnitude) galaxy is located only 8' south of 2.6-magnitude Delta (8) Leonis, the northern star of the triangle marking the Lion’s hindquarters. The galaxy was discovered by Lewis Swift with a 15-inch refractor and can probably be seen in smaller instruments. The bright star in the same field of view, however, will make this small object difficult to see.

In the Sickle of Leo is an interesting sprinkling of faint galaxies between Gamma (y) and Zeta (Q Leonis. NGC 3162 looks 2' in diameter and of magnitude 11-4 to my eye. Farther south and cast is tiny 12th-magnitude NGC 3177. Visually ¹¹ appears as an almost circular disk less than T across, which seems to bear high powers well. A bit farther east and nearly on the line between Gamma and Zeta ^,s a fancy threesome of small galaxies arrayed almost end to end. The middle and brightest is 1 lth-magnitude NGC 3190,about 3' x l'.To its southwest is NGC 3185, magnitude about 12.3 and 1.5' x 1'. At the other end of the chain, NGC 3193 is brighter (11.4) but only T in diameter. These three objects are an attractive sight °n a good night in the low-power field of a large amateur telescope.

^My old notes contain a reminder to look for the very faint galaxy NGC 3130 ^lbat should be in the same field as 31 Leonis, a 4th-magnitude star 2° south of same field will make this observation very difficult at best. NGC 3130 is a small faint galaxy of about 14th magnitude. It has eluded me for years, and I h_avJ never met an amateur who has seen it. I suspect that the naked-eye star hinders the view. Certainly many amateurs routinely observe fainter galaxies, so perhaps someone using an occulting bar in an eyepiece will be able to see NGC 3130

Finally, for those of you who really want an observing challenge, try searchin for any of the numerous galaxies that surround Iota (t) Leonis. A chart from an out-of-print star atlas published by the Smithsonian Astrophysical Observatory shows almost every square (each is about 1° on a side) containing a half dozen or more galaxies. With just a few exceptions, these objects are listed in the second Index Catalogue to the NGC. Most were discovered photographically by Max Wolf using the 16-inch Bruce refractor at the Heidelberg Observatory j_nGermany around the turn of the century. While many of the objects are small and faint, I suspect that many are within the visual grasp of a 17-inch telescope. Happy hunting!

Lure of the Little Lion

Leo Minor is tiny, covering only 232 square degrees of sky. It is one of the "most barren parts of the sky to the naked eye," Scotty said, yet he seemed particularly attracted to this dim constellation, which contains a rich assortment of galaxies within the range of small and modest-sized telescopes. Interestingly, before such cartographic wonders as Wil Tirion's Sky Atlas 2000.0 and the Millennium Star Atlas, observers had to work with less-detailed star charts, which were effective and helpful for their time but became problematical as the hobby grew. The Skalnate Pleso Atlas of the Heavens (a product of the 1940s and '50s), for example, plotted but did not number galaxies fainter than around magnitude 11. Furthermore, unless a backyard observer had access to an astronomical library, data on many of these objects were simply unobtainable. When large-aperture telescopes became increasingly available to photon-thirsty amateurs, Scotty was among the first to recognize our need for more adequate deep-sky star charts and catalogs. It is in part thanks to his constant dipping into the inner sanctum of the night that amateurs enjoy better reference materials today.

W' hen William Tyler Olcott wrote his classic A Field Book of the Stars around the turn of the century, he began the text with Ursa Major. Not only was this “the best known of the constellations,” but the stars of the Great Bear could act as guideposts to other parts of the sky. As an example, consider the undistinguished constellation Leo Minor. It was created by Johannes Hevelius during the wild proliferation of constellations that occurred during th^e17th century, when no part of the sky was immune to celestial cartographers-Some, such as Scutum Sobieski (now called Scutum), filled a visual void and still survive today. But others — Musca Borealis, Noctua, and Bufo, for example

, lone since been forgotten. Leo Minor is unusual in that it contains no bright designated Alpha (a), though it does have a Beta (P). Of the 88 constellations ently recognized, only three others — Norma. Puppis, and Vela — are with-^CUrr_an Alpha. But it can easily be tracked to its shady lair by following the stars ^the Bear’s hind legs. If we begin with Gamma (y) Ursae Majoris. in the Big ^,n. _r-_s Bowl, we can sweep down a line of stars curving southwestward and nding at the pair of 3rd-magnitude stars Mu (p) and Lambda (A.) Ursae Majoris. ^C Just 1° due west of Mu is the l()th-magnitude spiral galaxy NGC 3184. Although still in Ursa Major, when the galaxy is centered in a low-power eye-. _t]ie stars at the southwest edge of the field are in Leo Minor. An 8-inch reflector shows NGC 3184 as a pale disk about 5' across with a brighter center. At 30x it looks much the way the well-known spiral M33 does in my 2-inch finderscope. Ronald Morales comments that NGC 3184 reveals a rather uniformly illuminated disk as seen with a 6-inch reflector at 35x. Tokuo Nakamoto of Temple City, California, glimpsed a hint of spiral structure and saw one star superimposed on the galaxy with a 13-inch telescope.

The largest and brightest galaxy in Leo Minor is NGC 3344.This spiral (Figure ⁵-⁹) stretches across more than 6' of sky and has a total visual magnitude of 9.9. ^My observing notes from 1956 mention a wide, 9th-magnitude double star ^ahout T east of the galaxy which interfered with the view. NGC 3344 lies midday between the naked-eye stars 40 and 41 Leonis Minoris, about 6° east of ^Zela (0 Leonis in the Sickle, or about 3° west of the 4th-magnitude star 54 Leonis. One cold morning I found the galaxy easily in my 4-inch Clark refr;_lctor. It is a nearly circular blob about 7' in diameter, being photographically spiral galaxy seen nearly face on. but the arms cannot be seen in small amateur instruments. With his 6-inch telescope at 50x, Morales found it to have a hint of a starlike nucleus.

Another large and bright galaxy in Leo Minor is NGC 2859. It is also one of the easiest to locate since it lies less than 1° east of the brightest star in neigh boring Lynx (Alpha (a) Lyncis). If you point your telescope at Alpha and wait 3/4 minutes with the drive turned off, the galaxy will be just north of the center of the eyepiece field. The llth-magnitude barred spiral galaxy appears as a somewhat irregular grayish patch 4' x 3' or smaller. In 1978 I estimated its visual magnitude to be 10.7. A 4-inch instrument shows NGC 2859 to have a bright center, and there may be just a hint of the bar visible. My old 10-inch reflector revealed the bar and traces of an outer ring. Florida amateur Brenda Branchett reports that her 6-inch reflector at 70x also shows hints of the galaxy’s outer ring In a 36-inch reflector at Tucson many years ago this object was bright and fascinating. It is said to appear as a faint patch in a 3!4-inch telescope at 45x.

NGC 3245 is an elliptical that’s about as bright as NGC 2859 and slightly smaller. It is reported to be faint in a 3-inch at 18x. There are two moderately bright telescopic stars nearby, 10' southwest and 7' southeast. Branchett also notes a string of stars in the field that enhances the beauty of the view. Visual observers have commented on the oblong shape (2' x 1') of this 10.5-magnitude elliptical ever since its discovery by William Herschel in 1785. The galaxy is not difficult for my 4-inch Clark refractor at lOOx. 1 once viewed it with the 20-inch Clark refractor at Wesleyan University, and, while it appeared larger and brighter than in the smaller telescope, I did not notice much additional detail. Nearby are some very faint galaxies.

The Atlas of the Heavens does not give the NGC numbers of galaxies that are fainter than magnitude 11, roughly, and of the 19 in Leo Minor 14 are thus unlabeled. The sizes of the ellipses representing these galaxies, though a good guide to angular extent, give little idea of whether they are easy or hard to spot.

Take, for example, the unlabeled pair NGC 3003 and NGC 3021. The former is plotted as a larger ellipse than the latter, yet a 10-inch will show NGC 3021 much more easily. I have known amateurs to see only one galaxy here and assume it is NGC 3003. The explanation is that NGC 3021 is both brighter (12th-magnitude) and more compact (T x 0.5'), so its great surface brightness makes it a fairly easy object if one knows where to look. I have seen it in Connecticut with a 4-inch. NGC 3003, on the other hand, is a full magnitude fainter, and its light is spread over an area of 5' x T, making its surface brightness much lower. Here in the mediocre skies of Connecticut, NGC 3021 is easy to acquire in the 4-inch Clark, but NGC 3003 requires an excellent night and careful searching-Once when NGC 3021 was seen at 60x, it took 150x to establish with certainty the presence of NGC 3003.

Even today there is still some confusion about the relative brightnesses ol jjese galaxies. My estimates of 12th magnitude for NGC 3021 and 13th for iCC 3003 agree well with the values listed in Betjvdr’s old Atlas Catalogue. However, the Revised New General Catalogue and Burnham’s Celestial Handbook reverse the order. Perhaps this is merely a typographical error that jj_as been copied. Many instances of such errors are known in the popular observing reference books. As more amateurs adopt largcr-aperture telescopes for deep-sky observing, and fainter objects are examined, more of these discrepancies will be found.

About 2° east-northeast of Beta (0) Leonis Minoris is the 12th-magnitude alaxy NGC 3294. which is easy to find since it is slightly west of the midpoint of a line joining the 6th-magnitude stars 35 and 38 Leonis Minoris. There is a star just southeast of the galaxy, which is some 3' x 1' in extent. Branchett comments that NGC 3294 required averted vision with her 6-inch at 43x. Joseph Schmidt in Ely. Minnesota, however, called it “bright” through his 6-inch f/11 reflector. The 12-inch Porter turret telescope at Springfield, Vermont, can show the central core, but no individual arms, at 200x. A comprehensive variable-star catalog, the General Catalogue of Variable Stars, prepared at Sternberg Astronomical Institute by Boris V. Kukarkin and fellow Russian astronomers, lists an unconfirmed llth-magnitude supernova visible in NGC 3294 in 1955.

NGC 3395 is another I2th-magnitude spiral, about 2' in diameter. Amateur telescopes will show it almost in contact with NGC 3396 at its northeast edge. These are interacting galaxies, but the bridge of material between them does not show in small telescopes. Has anyone viewed them with a 30-inch aperture?

Navigating Sextans

The southern sky is littered with constellations that celebrate the scientific renaissance of the 17th and 18th centuries "like debris from an old-time science lab hit by a tornado," Scotty once quipped. Among these time-honored instruments you will find a set of navigational tools — namely an octant, a sextant, and a mariner's compass. "I suspect if a drift meter had existed when the constellations were named," Scotty continued, "we would even have included it in current lists of star patterns." As a former celestial navigator with the U. S. Army Air Force, Scotty was naturally partial to the constellation of the sextant, claiming that "at one time I m sure I took better care of mine than I did of my wife and children!" Ironically, Sextans is a challenge for beginners to navigate. Spanning an area of approximately S14 square degrees, Sextans ranks 47th in size of the 88 constellations. Its brightest ^star' Alpha (a) Sextantis, shines meekly at magnitude 4.5 and is easily lost in modest moonlight or light pollution, leaving that region of sky appearing totally blank. $° Scotty figuratively pulls up a chair, sits beside you at the telescope, takes a P^u,f of his pipe, then explains how to star-hop to the sole prize of Sextans, the ^bri8ht lenticular galaxy NGC 3115.

The first constellations were modeled after familiar objects that reflected th_clife and times of people millennia ago. There were farm carts, boats, bears fishes, and sea monsters. In the beginning each village may have had its own sei of constellations. But as thc villages developed into cities and the cities i_ntonations, individual lists became homogenized into one. The sky patterns w_eknow today are an amalgamation of those from dozens of long-ago empires.

After the chaotic early history of the constellations, they remained essentially unchanged in the Western world from about 275 B.C. to A.D. 1500 thanks to th_ewide acceptance of lists compiled by Aratus and Ptolemy. But then began anoth. er period when new constellations appeared on star charts and celestial globes No recognized constellation was eliminated, but many had their edges nibbled away to make room for the new and usually tiny groups. For each of these patterns we know the creator and in many cases even the exact words he used to defend his actions.

Furthermore, during this time explorers opened routes to the Southern Hemisphere where a whole new sky ripe for European constellation makers awaited. Scientists couldn’t resist filling the sky with star patterns commemorating their scientific instruments. They were acting very much like their agrarian ancestors — putting the tools of their trade into the sky.

One of my favorite constellations from this scientific renaissance is Sextans, the device navigators use to measure star altitudes. Hevelius formed the group in 1687 to commemorate the huge instrument he used to measure star positions from his rooftop observatory in Danzig (now Gdansk). There is, by the way, another such instrument at the south celestial pole. Octans, named for the octant of John Hadley, is a slight variation of the older sextant. Both instruments do essentially the same job, and some navigators have used the terms interchangeably.

On modern star charts. Sextans is merely a neatly bounded sky area, almost a perfect square. Inside this square the Skalnate Pleso Atlas of the Heavens shows nine galaxies, most of which are fairly difficult objects. By far the most prominent one is NGC 3115. This is an elliptical galaxy about 4' x 1' across. Its visual magnitude is given as 9, but this seems a little bright to me. NGC 3115 is bright enough to be seen in a 2-inch finder and even large binoculars. Tire problem is trying to locate it in such a star-poor region. This is a perfect place for the experienced beginner to practice star-hopping, that essential technique of correlating a star chart with the view in a finder.

Amateurs can never become too proficient at finding their way around the sky. Observing can lose some of its appeal when it takes 20 minutes to find an object that you may look at for only a minute or two. Some years ago I kept a record of how long I and others spent searching for variable stars compared with the time we spent making the magnitude estimates. I was amazed to discover that roughly 90 percent of our time was devoted to the search. It made little difference whether the observer used an altazimuth or equatorial mount since even an equatorial with setting circles usually just puts you close to the object of interest. You still must star-hop to center the field in the eyepiece.

Burnham suggests trying to locate NGC 3115 by sweeping 20° south from bril-• _nt Regulus in Leo. Even with setting circles, 1 wouldn't bet money on making 20° leap to land on a lOth-magnitude galaxy. Philip Harrington, in his book U^,,iverse Through Binoculars, suggests finding the galaxy by sweep-. 8° east from Alphard (Alpha (a) Hydrae) to pick up the stars 17 and 18

Sextantis. NGC 3115 is about I/2⁰ northwest of the pair. The problem here, how-_ver is that you can confuse 17 and 18 Sextantis with another pair nearby and "■nd up in the middle of nowhere. Each of these methods is handicapped by try-•_n0 to make too-long jumps using too few stars.

r is much better to plan a series of small moves, each covering no more than the field of your finder. This way you can always check your star chart to be certain where you are. One word of warning: star-hopping is nearly impossible if you have a finder that produces a mirror image of the sky — and such is the case with virtually all right-angle finders. Very few people can mentally transpose a mirror image to make it match a chart.

So where do we begin our hop to NGC 3115? Regulus is too far away, as is Alphard. Alpha (a) Sextantis would be a good choice except that there are several vacant spots along the way to the galaxy, making this a dubious ploy. Instead, let’s begin at Lambda (X) Hydrae (Figure 5.10). Not only is this an easy naked-eye star, but a distinct asterism formed by several surrounding stars will offer positive identification even in small finders.

Front Lambda, move about I/2⁰ north-northwest to a 7th-magnitude star eas-’ly identified by two slightly fainter companions to its southwest. About 2° north-^West °f this group is another 7th-magnitude star, this one at the northern end of ^a sprawling W-shaped asterism about 1° long and oriented roughly north-south. From here it’s an easy 2° jump northeastward to the distinct east-west pair formed by 17 and 18 Sextantis. Now a 1° hop to the northwest brings you to the °ther pair of stars mentioned earlier, and this puts you within striking distance ^of the galaxy, !6° due west.

Another method for locating NGC 3115 is especially good if you are ready f_Ora short coffee break during your observing schedule. Select an eyepiece which shows at least a Moon’s diameter of sky. and place the 5th-magnitude star Gamma (y) Sextantis near the southern edge of the field. If you leave the tele scope stationary for 12% minutes (turn the drive off if the telescope has one) the galaxy will be centered near the northern half of the eyepiece field.

The sole extragalactic prize of Sextans is the bright lenticular galaxy NGC 3115, also known as the Spindle Galaxy. It appears edge on; no dust lanes or spiral arms are visible.

And what a splendid sight NGC 3115 is (Figure 5.11), especially when you realize that few amateurs ever observe this island universe. Aptly named the Spindle Galaxy, it is an evenly illuminated elliptical about 4' long and 1' wide. Powers as low as 20x will show the spindle shape. Though I have observed NGC 3115 with a 4-inch telescope from Connecticut, averted vision was occasionally needed to find it. In a 5-inch Moonwatch Apogee telescope the galaxy appeared small but sharp. Smyth writes in the Cycle of Celestial Objects that it was very clearly distinguished in his 6-inch refractor. Many years ago I viewed it with my 10-inch reflector under the diamond-clear skies of Kansas. Burnham notes in his Celestial Handbook that the galaxy appears much the same to the eye in an amateur telescope as it does in photographs made with large telescopes. It has been classed both as a highly flattened elliptical galaxy and as an edge-on spiral. It lacks any hint of a dust lane, however, which shows frequently in edge-on systems. I think it fascinating to find an object that shows well in 5-inch binoculars, looks similar in a 12-inch instrument, and still perplexes professional astronomers working with the largest telescopes in the world.

j!^sl = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dork Nebula; GC = Globular Cluster; Gx = Galaxy;

¹ - Open Cluster: PN = Planetary Nebula; ♦= Star; ** = Oouble/Mulliple Star; Var = Variable Star

Ast = Asterism; BN = Bright Nebulo; CGx = Cluster of Galaxies; DN = Dork Nebula; GC = Globular Cluster; Gx - Galaxy; OC = Open Cluster; PN = Planetary Nebula; * = Star; ♦ » = Double/Multiple Star; Vor = Variable Star

The Bowl of Night

Never setting from mid-northern latitudes, the Big Dipper endlessly circles the North Star and is arguably the most sought after star group in the heavens. For centuries it has been one of humanity's most important celestial guideposts and remains so today. Tyros of all ages turn first to it to get oriented to the sky and to determine the scale of the patterns they see on their star charts. Telescope users soon learn that the Big Dipper and its parent constellation, Ursa Major, harbor a fleet of deep-sky objects, several of which belong to the Messier catalog. Scotty has already introduced us to two of these splendors — the Dynamic Duo of M81 and M82. Now he leads us into and around the Dipper's Bowl, which abounds in deep-sky delights for beginning and advanced amateurs.

One of the nicest pieces of celestial real estate for hunting down cosmic treasures is the area around the Bowl of the Big Dipper (Figure 6.1). Aside perhaps from Orion, the Big Dipper is the sky’s best-known star pattern, with bright, easily found starting points for star-hopping to deep-sky objects. And what a wonderful selection of objects there is, for it is here in the polar region that the great stream of galaxies reaching northward from Virgo and Coma comes to a brilliant con elusion. Several bright galaxies from the Messier catalog bedeck the Dipp_eramid scores of others that are easy targets for 6-inch telescopes.

Unlike objects far to the south that can only be seen to advantage for an hour _Ortwo when they cross the meridian, those in the polar sky can be profitably studied for many hours each night and for many months of the year. In late spring the flower basket of the Big Dipper’s Bowl rides nearly overhead during evening hours,

Figure 6.2 M97, the famous Owl (lower left), is a planetary nebula with two dark "eyes." Less than a degree northwest lies the remarkable spiral galaxy Ml 08, which is inclined only 8° from edge on.

Close to thc southern edge of the Big Dipper’s Bowl is the remarkable planetary nebula M97, popularly known as the Owl (Figure 6.2). At magnitude 11.2, M97 is second only to the planetary nebula M76 in Perseus (magnitude 11.5) as the faintest object in the French comet hunter’s catalog. Nevertheless, M97 is no problem for 4-inch telescopes, and I have easily seen it in 15 x 65 binoculars. The two dark spots that form the Owl’s “eyes” are more challenging, but under good skies they might be within range of a 4-inch telescope. The nebula measures only 3', and if it is not seen at once, let your eye wander aimlessly over the field of view until the disk springs into view. Barns, in his 1001 Celestial Wonders, calls this object dull-toned, but memorable. William Herschel long ago thought it was a cluster of stars, unresolvable because of its immense distance. Even though today we know of planetaries three times farther, this object’s distance of about 10,000 light-years will make many share Herschel’s feeling of its remoteness.

Strangely enough, William H. Smyth could see nothing but a pale, uniform disk “about the size of Jupiter,” yet a 6-inch today will show something of the two dark holes in M97. But Smyth wrote before Lord Rosse found them, indicating that it is much more difficult to discover something than to confirm it. My 10' inch, under clear Kansas skies, shows the full 3' diameter of the Owl.

the same low-power field. Another way to find it is to start t the Dipper’s Pointer Stars, Alpha (a) and Beta (0) Ursae 4^C spacing as a gauge, shift l'Z^o southeast of Beta and try to streak. Although Messier did not include this object in his catalog, handwritten notes in his personal copy of the work ware of it. During the 20th century, several astronomers who c proposed that this galaxy and six others known to Messier the original list, bringing the total to 110. The galaxy is a , 8' x 2' in extent, of magnitude 10, with a faint foreground star superimposed. Herschel listed it as Number 46 in his class V (very large nebulae) and therefore Norton's Star Atlas marks it as H46\ It is easily seen in 50-mm binoculars.

photographs reveal it as an edge-on galaxy. The dim central condensation has been reported as just visible in a 3/2-inch refractor. Regardless of the telescope’s aperture, try a high magnification on this spiral. At 30x, the 12-inch Porter turret telescope showed lots of delicate internal structure. In some ways, M108 is similar to M82.1 wonder if the excessive hydrogen-alpha light known to come from M82 would cause the galaxy to appear different from M108 when both are observed through various nebula filters.

Now move to Gamma (y) Ursae Majoris, the southeastern star of the Bowl. Just ^!/,° southeast of this star is a 9'/’-magnitude galaxy, M109. Oval in outline and several arcminutes long, this one is bright and easy in my 5-inch Apogee telescope. Older catalogs call it only NGC 3992. Its Messier designation dates from 1953, after Owen Gingerich of Harvard Observatory discovered a previously overlooked note concerning it in Charles Messier’s personal copy of a 1784 French almanac (discussed on page 127 in “The Mystery of M102”). In my 5-inch Apogee telescope at 20x, this galaxy seems brighter than its cataloged magnitude of 10.8. I can even catch its 6' x 10' shape in 15 x 65 binoculars. I know of no amateur sightings of the galaxy’s arms or central bar, which show well on photographs. Visually NGC 3992 looks like a featureless oval glow surrounding a brighter core. There is a 13th-mag-nitude star near its northern edge. In 1956 a supernova in this galaxy reached magnitude 11.2, which was well within the grasp of amateur telescopes. This galaxy is thus a good candidate for inclusion in a visual supernova-search program.

Returning to Gamma, slew the telescope south 6° and center on 3.7-magnitude Chi (X) Ursae Majoris; then go east another 6°. In the telescope’s low-power field, there should be seen an oblong diffuse patch, the 8th-magnitude galaxy M106,just across the boundary of Ursa Major in Canes Venatici. If the night is good, you may also glimpse NGC 4217, a smaller galaxy !4° west of M106.

Tile Dipper’s Bowl also contains a fair number of 1 lth-magnitude and fainter galaxies which generally go unmentioned in amateur observing guides. Norton’s H°^r Atlas plots seven galaxies inside the bowl, and the Skalnate Pleso Atlas of the ^eovens adds another five. During a visit with members of the San Jose Astronomical Association in California. 1 found that Gerry Rattley and com_ediscoverer Don Machholz are quite familiar with these objects. As none of th_cgalaxies have ever been mentioned in this column before, let's take them up _noxv

One of the brightest objects is the spiral galaxy NGC 3982. It is surprisin i easy to spot in my 4-inch Clark refractor, and appears as an 11.3-magnitude blu about T in diameter and slightly oval.

Another spiral, almost as bright at magnitude 11.4 and nearly twice as lar»_e i NGC 3898. NGC 3610 is similar in brightness to NGC 3898 and is a tiny ellip_tj^Scal galaxy only about 1' in diameter. My only observation of it was from Kansas in May 1956, with a 10-inch f/8.5 Newtonian reflector. NGC 3613 is a distinctly oval galaxy about IZ'long. My magnitude estimates of it average 11. And at pho-tographic magnitude 13. NGC 3683 is a difficult object. NGC 3894 is very faint while NGC 3690 is a little easier as its visual magnitude is about 12.0.

NGC 3642 is an interesting galaxy. Although its total light, equivalent to an 11.4-magnitude star, is spread over a patch some 5' across, this galaxy is not too difficult to find. Indeed, in the same 1956 observing journal in which 1 recorded NGC 3610,1 noted NGC 3642 as a beautiful sight in the 10-inch, even at 200x. I use a Barlow lens rather than a short-focal-length eyepiece for highly magnified views of deep-sky objects. The Barlow seems to add less scattered light to the field, thereby improving the contrast between the sky and galaxy or nebula. NGC 3619 is about magnitude 11.7 and T in diameter. In my 4-inch Clark it is best seen at lOOx or more. With lower powers it could be mistaken for a faint star. Slightly fainter but easier to find is NGC 3738. Still dimmer is 12th-magni-tude NGC 3756. This spiral galaxy is about 3' long and half as wide.

I have also selected five galaxies located north and east of the Bowl. All are moderately faint, but surprisingly easy in average skies. NGC 4036 is a large diffuse glow, 2.4' x 0.9' according to Sidney van den Bergh's revision of the Shapley-Ames Catalog. Some searching was needed to find it in a 5-inch richfield Apogee telescope, but once located it was readily visible as 1 Ith-magnitude, fading off at the edges. In the same field is NGC 4041. Of about the same size and brightness, these galaxies look like twins, but actually NGC 4036 is elliptical. NGC 4041 spiral.

Brightest and easiest to find in our quintet is NGC 4605. This lOth-magnitude spiral lies nearly on the extension of a line joining Gamma (y) and Delta (8) Ursae Majoris. It is obvious in 65-mm binoculars, and a large telescope makes it a fine sight, extending across a 5' x 1.2' area of sky. Equally nice is NGC 3945. an 1 lth-magnitude barred spiral. Covering an area measuring 5.2' x 2.2', it is fairly easy to find and most interesting in large telescopes.

The final galaxy. NGC 4814, is a barred spiral a little more than 2' in diameter. But do not be surprised if you should come across other objects in and around the Bowl. There are more galaxies here within reach of today’s larger amateur telescopes. Observers with 8-inch and larger telescopes will find an almost endless supply of galaxies in the area. Indeed, the Uranometria 2000.0 atlas plots 50 I within the Dipper’s Bowl. Hunting some of them down is a pleasant way to j^uSl d an evening under the stars.

The Mystery of M102

of the oldest and most unrelenting mysteries to haunt the pages of astronomical Mature is Charles Messier's enigmatic 102nd catalog entry. For many years M102 ad no proper identity — no ceep-sky object exists in the terribly rough (and bviously wrong) position provided to Messier by its discoverer, Pierre Mechain. Over the years, however, a handful of celestial detectives have challenged themselves to solve this centuries-old mystery. Some sleuthed the sky for clues. Others perused the dusty pages of old journals searching for an answer. Indeed, as Scotty explains here a major discovery in Canada finally resolved the matter. But did it? Alas, the answer is yes, but also no. Despite indisputable evidence, many amateurs to this day do not accept the Canadian discovery, opting instead to espouse and promote their own theories for the identity of M102. In the end, in the inimitable words of Scotty, "one wrong assumption coupled with immaculate logic produced a can of worms."

Amateur astronomers are a persistent lot. Give them a problem, and they can spend years chipping away at it. The late Leslie Peltier checked the star T Coronae Borealis on thousands of nights beginning in 1920. In 1866 it had briefly become a naked-eye nova, and for decades thereafter it remained a rather unremarkable lOth-magnitude object. Peltier’s vigil was an act of faith, since the star had no known history of repeated outbursts. But on February 9, 1946, the star again rose to easy naked-eye visibility at 3rd magnitude. Although Peltier wasn’t the first to note the brightening, the outburst vindicated his years of effort.

In the 1930s Joseph Meek noticed a slight, rapid cycle in the light curve of the dwarf nova SS Cygni and began wondering if the star was a close binary. It would be 20 years before spectroscopic observations at Mount Wilson Observatory proved him right.

Texas amateur Oscar Monnig had taken an early interest in photographing the spectra of meteors. Before professional astronomers turned their attention (and vastly greater resources) to this difficult task. Monnig took about half of all the "'orld’s meteor spectra.

Recent history abounds with similar stories. Most have never been written down and are preserved only in the fragile vessel of oral tradition, which has a life-^SP^an usually limited to that of the people who were there.

Rut the enthusiasm of amateurs sometimes leads them astray. Take, for exam-P^c- the case of M102. In 1781, Charles Messier prepared the last supplement to list of nebulae and clusters and published it in the French almanac uuaiwa/ice des temps. As in earlier installments. Messier included several ^Jects discovered by Mechain. These were listed as numbers 101, 102, and 103. Unlike M6chain’s previous objects, however. Messier did not observe thes three himself. Furthermore, he lacked precise positions for M102 and M103 Mechain only gave positions relative to surrounding stars.

Soon after the publication of Messier’s final supplement. Mechain wrote a |_etter that appeared in Bode’s Astronomisches Jahrbuch for 1786. In it he stated that object 102 was actually a duplicate observation of 101, but due to an error on his star chart he originally thought it was a separate nebula. At the time it _Wasconsidered no big deal — mistakes sometimes happen.

What turned this mistake into a big deal was that most astronomers remained unaware of MSchain’s letter. Later editions of Messier’s catalog failed to correct the error. Thus, M102 became one of the “missing Messier objects." As with M47. M48, and M91, its absence fascinated observers ever afterwards. Amateurs, especially. have delighted in trying to track them down, offering all sorts of explanations for why the positions in the original listing were wrong.

In his 1844 Bedford Catalogue, Smyth made a case for Ml02 being the galaxy NGC 5866. He argued that Mechain's original position for Ml02 — between lota (1) Draconis and Omicron (o) Bootis — was too vague even for a skilled observer to find it. Instead, Smyth assumed that Mechain had misread his own handwriting and the star he meant was not Omicron but Theta (0) Bootis (as you can see, omi-crons and thetas can look somewhat similar). Smyth’s “revised” position defined a much more precise location and pointed the way to NGC 5866, which is the brightest of five galaxies in the area.

ms. Smyth was one of the most respected amateurs of all time, so you can see jjjs proposal that Ml02 was really NGC 5866 gained stature. So much so that '^vl1' the Canadian astronomer Helen Sawyer Hogg uncovered Mcchain’s letter * 1940s, her “proof’ that Ml02 does not exist met with amateur resistance.

¹¹ whatever reason, in the hearts of many observers NGC 5866 remains as ^^f.)2 _even to this day. But there is little doubt that M102, as published by sier, is really just M101 repeated with the wrong position (Figure 6.3).

NGC 5866 could well have been included in Messier's catalog. Mechain proba-would have seen NGC 5866 had he happened upon it with his telescope. With _maonitude of about 10.5 it is brighter than some of the catalog's other entries, and it is easily recognized in a 3-inch telescope. On excellent nights I have seen its rather narrow, 3'-long shape through the 2-inch finder of my Clark refractor.

The growing popularity of Messier clubs, however, causes the following question to be asked more often: If an amateur aims at personally observing each of Messier’s 100-odd nebulae and clusters, what should be done about M102?

The Deep-Sky Triangle

The night sky is replete with deep-sky wonders. "It's difficult to imagine anyone viewing every object within reach of a 6-inch telescope," Scotty said, "not to mention a 12-inch." One problem he noticed with beginners who wrote to him was that they often wondered where to start. Should they work like bird watchers who refer to life lists and methodically check off each item? One obvious reply would be for them to start out by viewing the 109 objects on the Messier list, then graduate to the catalog compiled by William and John Herschel. Others would suggest seeking out all the objects of a particular class. Do you like globular clusters? Well, you can obtain lists of all the globulars visible to a certain magnitude limit and start checking them off. The same goes for planetaries, galaxies, and double stars. Scotty, however, was not your mainstream correspondent. If you wrote asking for advice, his response would not be trite. Scotty was keen on devising new ways to explore the heavens, and he welcomed the challenge of blazing new trails for beginners. Thus was born, for lack of any "proper Scottyism," his Deep-Sky Triangle.

r he memory of winter begins to ebb in June as mild but crisp nights complement I the celestial riches now in the sky. Arcturus shines overhead, and Corona Borealis, the Northern Crown, is at its dainty best. Draco coils in pinpoint stars about the ecliptic pole, and the great globular star cluster M13 is climbing up the ^eastern sky. It doesn’t matter if you use binoculars or a 20-inch telescope, there ^ls so much to see that you wish for an impossible succession of crystal-clear ⁿ'ghts — but where to begin?

One way to start your assault on the night sky is by selecting an area defined y several bright stars. With the aid of a good star atlas, wc can then seek out all ^e objects in this area. For example, this month let’s take the triangle of stars

Seeking out all the astronomical treasures within the Deep-Sky Triangle — formed by Eta (T]) Ursae Majoris, Alpha (a) Canum Venaticorum, and Gamma (y) Bootis — is a good way to start your "assault" on lune's night sky. North is to the upper left.

Figure 6.5 M51, the Whirlpool Galaxy, is popular among photographers and visual observers because its spiral structure is so easily resolved. The small companion galaxy is NGC 5195.

e 6.4) formed by Eta (q) Ursae Majoris. Alpha (a) Canum Venaticorum, K*Gamma (y) Bootis, found hanging on the end of thc Big Dipper’s handle. ⁸ lance at Tirion’s Sky Atlas 2000.0 shows that at least a dozen galaxies lie 'thin ^l*^ie triangle. J^ust mside and outside its western edge, several notcwor-examples are M51, M63. and M94. which can all be seen in binoculars nder good conditions.

^U This part of the sky is far front the plane of the Milky Way so, as we might expect- there are no prominent star clusters nearby. M51. the Whirlpool Galaxy ,_{F eu}re 6.5), lies just outside the triangle about a quarter of the way from Eta Ursae Majoris to Alpha Canum Venaticorum. Messier found the galaxy in October 1773, while observing a comet he had discovered. Eight years later jvlechain noted that the galaxy was double. He saw the two components as clearly separated centers with halos touching one another. Today, nearly every amateur telescope will show M51 (with its companion NGC 5195). Even through smog and thin clouds a 6-inch will reveal the two components that such 19th-century observers as Smyth and Thomas W. Webb wrote so enthusiastically about.

The Whirlpool offers challenges for any telescope. For example, what is the smallest aperture required to reveal the spiral structure? Lord Rosse first detected spiral structure when he turned his giant 72-inch reflector on the galaxy in the spring of 1845.Today, with our vision sharpened by knowledge, the spiral features of M51 are visible in instruments as small as 10 inches, and some observers have glimpsed them with 6-inch telescopes in very dark skies. An 8-inch is sufficient for me, but John Mallas needed a 12'Z-inch in a dark desert sky. He correctly noted that experience and exceptional transparency are important for success. In 1936 I had a very good view of the spiral structure using the University of Arizona's 36-inch reflector in Tucson.

In clear, dark skies, an 8-inch at 40x will show the brightest portion of M51 to be about 11' long and 8' wide. Increasing the magnification to 200x, especially when the seeing is good, may reveal considerable structure in the disk, which at first glance appears rather uniform. Observers can also try to detect the “bridge” of light that connects the two galaxies. Again. I have seen it clearly with an 8-inch, but Mallas drew it as it appeared through only a 4-inch. Yet he recalled that perhaps he knew the field too well from photographs, and his observation may have been biased. Some amateurs have followed the entire bridge using a 17.5-inch in the clear desert skies of the American southwest. I have even seen traces of it here in Connecticut. The real key to viewing it is sky transparency, ^Slnce the slightest moonlight or light pollution renders it invisible.

A third challenge was proposed by Ronald Morales of Tucson, who observed fr°m the Santa Rita Mountains southeast of the city. Using a 10-inch f/5.5 reflector with a 16-nim Konig eyepiece, he steadily held with direct vision a faint star ^suPerimposed on the southwest quadrant of M51’s disk. I wonder how small ® telescope will reveal this star. I failed to see it with a 4-inch in good skies, owever, I suspected the bridge, which apparently was not seen by Morales on the night lie noted the star. West of M51's center, and superimposed on th. galaxy’s disk, is a foreground star that is occasionally mistaken for a supernova

About !4° south of M51 is a much more difficult object, the small elliptj_CaJ galaxy NGC 5198. It is round, 2' in diameter, and I estimate it as magnitude 12 '•> High magnification is useful when searching for this small object, as it can look rather starlike at low powers.

Moving southward, the bright galaxy M63 is about two-thirds of the wav from Eta Ursae Majoris to Alpha Canum Venaticorum, and as far inside the triangle as M51 is outside. Mechain discovered it in 1779 (Figure 6.6). At magnitude 8 6 it is apparent in any telescope, and I have seen it well in a 2-inch refractor. On another occasion, while using a 29-inch, I caught sight of the faint spiral arms surrounding M63’s bright core.

Figure 6.6 M63 is a rare type of galaxy whose many spiral arms bear a rash of star clouds. Its dappled appearance gave rise to its nickname, the Sunflower Galaxy.

Alpha Canum Venaticorum is popularly named Cor Caroli, the heart of Charles. Legend attributes the name to Edmond Halley, who was honoring his benefactor, England’s King Charles II. There is less than solid proof of this, however, and some question remains as to whether the honor was intended for Charles I. Sweeping just over 1° southeast of Cor Caroli brings us to a pair of faint galaxies. NGC 4914, at 12th magnitude, is brighter and larger than NGC 4868. Both should be within range of an 8-inch, given a dark enough sky.

NGC 5005 is located about 1 !4° farther to the east-southeast. At magnitude 9.8 and 5' long, this slender spindle of light is better known than either NGC 4914 or NGC 4868. Look for another galaxy, NGC 5033, roughly 1° southeast of NGC 5005. It would be especially nice to observe this object with an aperture of 20 or more inches. I suspect that some internal detail is visible, though none is app^ar' ent in an 8-inch telescope.

■[

pjcar the midpoint of the triangle's southern edge is a loose swarm of galax-yVc can begin with a group of three that lie in a north-south line within the ^lCS\e low-power field of view. Even casual sweeping of the area should turn them up. The largest (nearly 3' in diameter) is the 11.4-magnitude spiral NGC 535O It shows up clearly at 20x in my 5-inch Apogee telescope, and I once saw • _at the annual Stellafane convention in Vermont with a 10-year-old girl's homemade 4-inch off-axis reflector.

Just 5' south of NGC 5350 — roughly half the distance between the famous double star Mizar and Alcor in the handle of the Big Dipper — lies a pair of galaxies almost in contact with each other. The southern one is the 11.1-magni-tude elliptical NGC 5353, which is cataloged as a bit over 2' in diameter. Just 1' to its north is NGC 5354, about the same size and perhaps half a magnitude fainter. Like NGC 5350, it is a spiral.

About Z° to the east of this triplet is the spiral NGC 5371. At magnitude 10.8 and some 4' in diameter, it should be an easy object in just about any telescope. An 8-inch telescope will show hints of internal detail, while my notes on the galaxy tell of one observer, using a 36-inch, who could sec faint arms and a prominent central bar. My 8-inch reflector shows what is cither a bright stellar nucleus or a foreground star superimposed on the galaxy's center.

NGC 5371 is the subject of an interesting and instructive tale. The galaxy was discovered by William Herschel, who called it “pretty bright, large, round, brighter middle with a faint nucleus.’’ It was also observed by his son John in May of 1831. John recorded no description of the object on this date, but during one of his sky sweeps two months earlier he “discovered” NGC 5390 located 20' east of NGC 5371. (For the sake of clarity I'm using NGC numbers, but these were actually added later. The Herschels used other designations.) John recorded the new object as “faint, large, very gradually brighter middle, with a 9th-magni-tude star to the northeast." He does not mention seeing NGC 5371 on the night he observed NGC 5390.

Today we know that there is no object at the position John gave for NGC 5390. I've even checked photographs of the area made with the Palomar 48-inch Schmidt telescope. A quick review of modern references, including Vol. 2 of Sky Catalogue 2000.0, reveals that NGC 5390 is a duplicate observation of NGC 5371, but 1 don’t know who first pointed this out.

There is little doubt that it was a duplicate observation. First, John didn’t see NGC 5371 on the night he “discovered" NGC 5390. Furthermore, the real NGC 5371 has a star just to its northeast that matches John’s description of NGC 5390. A slight error in recording the object’s position would make it seem like a discovery. But why did John call the galaxy “faint" and his father say it was “pretty bright," when both were using the same telescope with an 18.7-inch speculum-^metal mirror? Perhaps the mirror’s surface was tarnished and in need of polishing °ⁿ the night John observed the galaxy.

goes to show that the descriptions in the New General Catalogue of id Clusters of Stars (NGC) are a rough approximation of what we can

The Wonder of M106

Aside from the "missing" Messier objects (M47, M48, and M91), the most intrig_Uj_naspect of Messier's catalog — one that arouses amateur interest, as Scotty believed^ — is the origin of its final seven entries. Messier's original catalog, published in installments from 1774 to 1 787, listed only 103 deep-sky objects, including one duplicate observation (M102), a double star (M40) and an asterism (M73). Indeed some observers resist the so-called "final seven" and argue that the true Messier catalog contains only 103 deep-sky objects. Earlier this century it was proposed and widely accepted that seven more objects be added to the Messier catalog for various and sundry reasons. "Of these additions," Scotty proffered, "the galaxy M106 in Canes Venatici is particularly interesting."

Charles Messier discovered a comet drifting through Ophiuchus on September 27, 1793. As he had done in the past, the French astronomer called upon his mathematician friend Jean-Baptiste-Gaspard Bochart de Saron to calculate its orbit. Readers with a bent for astronomical history may recall the unusual circumstances surrounding this event. Bochart de Saron had been imprisoned during the French Revolution’s Reign of Terror and was awaiting execution when he received word of Messier’s new comet. Nevertheless, he worked out an orbit, which Messier used to recover the comet after its conjunction with the Sun. Messier was able to slip his friend word of the success before the guillotine’s blade fell on April 20,1794.

I wonder if other aspects of the Reign of Terror have trickled down through history to affect today’s amateur astronomers. Certainly Messier’s work must have been affected during the Revolution. Had it not been, he might have caught and corrected some of the errors that appeared in his original catalog — errors that continue to fuel star-party debates as amateurs speculate on the true identity of several “missing” Messier objects.

Another aspect of Messier’s catalog that arouses amateur interest is the final seven entries. An original paper by H. S. Hogg, in which she describes five of these seven objects, and which deserves to be read by every amateur as a lesson in industry, appears in the Journal of the Royal Astronomical Society of Canada. September 1947. Of these additions, the galaxy Ml 06 in Canes Venatici is particularly interesting (Figure 6.7). Descriptions of its visual appearance vary considerably. Photographs are of little help in resolving the discrepancies since the differ' ence between them can vary almost as much. (Even prints made from the same negative will look different depending on how they are exposed and developed.)

Hans Vehrenberg’s Atlas of Deep-Sky Splendors includes a shot of M1^ made with the 200-inch Hale telescope at the Palomar Observatory, as well as a

The peculiar galaxy Ml06 in Canes Venatici has had a violent past. Its arms are scarred with material blown out of the galaxy's nucleus during vast interstellar storms.

wide-field view made with a 12-inch Schmidt camera. The 200-inch photograph gives the impression of a barred spiral seen almost edgewise, but in the image made with the smaller telescope M106 looks more like a regular spiral. The truth probably lies somewhere in between, since M106 is classified as a peculiar Sb spiral in Sky Catalogue 2000.0.

Ronald Morales viewed M106 with his 10-inch Newtonian reflector. Using 87x he described it as “extremely large; very bright with a bright, compact center; extended in a north-south direction with a large, fuzzy outer envelope. Years ago in Kansas 1 viewed the galaxy with a 10-inch reflector at about the same magnification and saw a “very bright parallelogram shape with fragile spiral arms at the ends of the major axis." The nucleus appeared uniform with little ^variation in brightness. Other observers using 8-inch telescopes have reported Ml 06 s appearance as long and needle-like, and one saw a dark area near the aucleus. So much for consistency!

Forgotten Corridors

Say the words "Virgo" or "Coma Berenices" to a seasoned observer and a knowing look will come over his or her face. If there is one area of the heavens beloved by galaxy hunters and hated by comet hunters (because it's so hard to spot a comet against all the other "faint fuzzies"), it is the great Coma-Virgo cluster of galaxies "Amateurs today tend to acquire larger and larger telescopes," Scotty explained, "_andthe constellations of Coma Berenices and Virgo offer challenges that take us beyond merely re-observing well-known objects. Since the North Galactic Pole is nearby there is very little interstellar dust in this direction, giving observers a clear window to the universe." But tackling this region for the first time can be a daunting task. Star-hopping is an acquired skill, one best practiced in a less galaxy-polluted region of sky. Naturally, Scotty was not at a loss for a better way. Here he introduces a fun and pragmatic technique practiced in the late 1700s, but largely forgotten or avoided today (because of the necessary time commitment). There are also several underdog objects among the opulence of galaxies. For instance, Scotty reveals a neglected corridor of globular clusters in the region. Another object, the largest and brightest in this vast area of sky, is obviously itself one of the sky's most uncelebrated hidden treasures.

ber, and was called “gossamers spangled with dewdrops” by the 19th-cen-tury astronomy popularizer Garret P. Serviss? Almost every skygazer has seen this group at one time or another, and its official designations are Melotte 111 and Collinder 256. The answer will surprise many, for the cluster is the shimmering haze of 5th- and 6th-magnitude stars we call Coma Berenices. It is a real cluster and not just a chance alignment of stars. There are about 80 members scattered across 5° of sky. A camera with high-speed film can record the cluster with an exposure of just a few seconds. Coma Berenices is only 260 light-years away and is one of the nearest open clusters. Therefore its stars appear well separated. If they are a bit too faint for your naked eye, a simple 2x or 3x opera glass gives a wonderful view.

Of course to observers of intergalactic depths, this region of sky belongs to the great clouds of spirals that dominate Virgo, Coma Berenices, and Canes Venatici. Less realized, perhaps, is that in these same regions we get the first onrushers of the globular clusters which finally swarm in their greatest profusion around the galactic center in Scorpius/Ophiuchus/Sagittarius.Three globulars are within the narrow limits of Coma itself, including two that lie near Alpha. NGC 5024 (M53) is 14.4' in diameter with a magnitude of 8.7. Unimpressive in a 3-inch refractor, its star sprinklings are magnificent in a 12/2-inch reflector, where faint streams of curving stars run out from the central blaze in all directions. Smyth called it an “interesting ball of innumerable worlds.”

Almost in the same field is NGC 5053, diameter 8.9', magnitude 10.9. In large instruments it is a little gem of woven fairy fire. Hogg’s Bibliography oflndivid“^a globular Clusters shows that it was first observed by William Herschel on March |4 1784. It is remarkable for its position in space, perhaps 50,000 light-years ,_ltlOve the galactic plane.

Considerably to the west of these two lies NGC 4147, magnitude 11. Its faintness misled Herschel, on the same date as that he first observed NGC 5053, into listing >t a^s something external, and only with the great reflectors of the 20th century could its individual stars be seen well and studied. We now know of several variable stars in this faint object.

In the same field lies a true faint external galaxy, NGC 4153, about 13' south and about 8' east of NGC 4147. It is not listed in the Shapley-Ames Catalog, and hence must be fainter than 13th magnitude. It would be a real feat for an amateur telescope to locate it. I have examined NGC 4147 on half a dozen occasions without noticing the faint galaxy.

In the western part of Virgo, galaxies are crowded like a confusion of silver sands. But eastward from the middle of the constellation, deep-sky objects are more scattered, and amateurs may have difficulty in locating some of them because easily identifiable stars are few.

There is a strip of sky here near declination +02° where several galaxies and a beautiful globular cluster can be readily located by means of a technique that dates back to William Herschel (Figure 6.8). Thc procedure is simple: set your

Herschel's 40-foot telescope was a veritable cosmic workhorse, which he used to plow up new deep-sky wonders.

telescope on a prearranged starting point, leave it stationary, and watch celcsf objects drift through the field according to a timetable.

For this purpose, use a low-power eyepiece with a field not much less thg I 1° across. To check the field size of an eyepiece, time the drift of an equate ■ ° star centrally across it, and count one minute of arc for every four seconds '* time. Once that’s completed select a star lying west of the desired galaxy hif having nearly the same declination. The telescope is then left stationary. allow ing diurnal motion to carry the object into the center of the field. The drift tim_erequired is the same as the difference in right ascension between the star and the galaxy.

Figure 6.9 You can find several galaxies and a globular cluster easily by letting the sky drift over your stationary telescope. Start your scan at the small galaxy NGC 5746.

Begin by picking up the elongated spiral galaxy NGC 5746, about Z<° west of the 4th-magnitude star 109 Virginis. It is a lOth-magnitude spindle about 6' x 1. less in small telescopes. A more difficult spiral in the same field. NGC 5740, hes about !6° to the southwest of NGC 5746. It is about magnitude 12, and 2' x 1 across.

NGC 5746 is the starting point for our strip (Figure 6.9). Center it in the ticlti-clamp the instrument, and be careful not to shift it during the remainder of the experiment. Then relax and watch the stars glide by. Keep track of the time that has elapsed since the starting object was in the middle of the field.

Consult a schedule of times at which some stars and deep-sky objects will P^asSthe midline of the eyepiece field. After a wait of about 13 minutes, the first fl ^a _of galaxies near 110 Virginis will appear at the edge of the field. Be care-^' "'ot to let the light of this star dazzle your eye when it comes into view about Lee minutes later.

I lic brightest of this little group is NGC 5846, a compact elliptical galaxy. I_V overlapping it is a much fainter but somewhat larger companion, NGC - L On an excellent night in 1935,1 found it was easy in a 4-inch.

After another gap of about 10 minutes the great globular cluster M.S swims to view (Figure 6.10). About /s° in diameter, it is one of the better globulars

Figure 6.1(1 End your scan at MS — a stunning globular cluster — which seems to float above the stars of Serpens. In between NGC 5746 and M5 lie several faint galaxies.

for small telescopes, because it actually gives the impression of being a cluster rather than an amorphous glow.

Tlte strip method of observing is a handy way of picking up an inaccessible object without using the setting circles on your telescope. From a star atlas select an easily identifiable star having nearly the same declination to the west, and find from their differences in right ascension how long to wait. Also, the stiip technique can be used to explore rich Milky Way regions this summer. You can obtain the approximate position of any object of interest by noting how long an 'nterval of time it follows the starting star, and by estimating how far north or ^s°uth of the center of the field it passes. By the way, on an exceptionally good ⁿ*8ht,can you see M5 with the naked eye, just north of 5 Serpentis?

Cup and Crow

One point Scotty often repeated in his columns was that when searching for faint objects, it is beneficial, if not imperative, to have a set of star charts with a magnitude limit of at least 9. "On such charts," he said, "there will almost alwa be one or two stars that appear in the same low-power field as the object of interest. This will help not only in locating but also in identifying objects misidentifying deep-sky objects is a sin common to both novice and experienced observers alike." As a case in point, he referred to a small group of galaxies near the border between Corvus and Crater. One of them, NGC 4038 (the famous Ring-tail Galaxy), he said, deserves special attention, because "several times amateurs have sent descriptions of what they believe is this galaxy, but I'm sure they have mistaken another galaxy for the Ring-tail." The clarification seemed particularly important to Scotty because he had an affinity for this region of sky- it took him almost 60 years to learn to appreciate Crater and Corvus, and he wanted to be sure that his readers got the full benefit of their efforts as they tipped their telescope tubes toward these southern celestial wonders.

There is never a shortage of deep-sky objects. Whatever the season, the sky holds more than enough of these delights to keep you busy all night, every night — if you take the time to search them out with good charts and reference books. Many deep-sky objects have special features to tantalize you. In the June evening sky, almost every direction we look offers something interesting. But near the meridian this month are two constellations that took me almost 60 years to learn to appreciate. Corvus, the Crow, and Crater, the Cup, seem like insignificant asterisms when viewed from the United States. 1 always found them delicate, with stars that had to be picked out from the background. They are not at all like Cassiopeia, Cygnus, or Delphinus, which almost force themselves on you. My feelings changed when I first saw Corvus and Crater from Central America.

William Tyler Olcott’s classic A Field Book of the Stars first made its appearance about the time Halley’s Comet swept through the inner solar system m 1910. Olcott’s outlines of the constellations were the only ones several generations of young astronomers knew, and many of his patterns are still accepted today. I especially like Crater, the Cup, perched precariously on Hydra and tilted as if to pour a celestial libation of stardust.

As a youth, I found Crater a lucid grouping of stars that was a delight to explore with a 1-inch, 40x refractor. Today, however, my mail indicates that fe^wamateurs pay much attention to this area of the sky. While many of the deep-sky objects here should be better known to amateurs, there are no spectacular ones to draw observers into the area. The light pollution surrounding urban centers leaves this faint constellation little admired.

n_urnham’s Celestial Handbook lists only 15 deep-sky objects down to magni-j, 13 in Crater. All but one are from the New General Catalogue of Nebulae ^tu alters of Stars.There are many fainter NGC objects in this part of the sky, ^fl/i -ell a^{s a num}'^5er °f others listed in the two Index Catalogues. Novice ⁸ ervers may find all this a bit confusing. Several years ago, when a 12-inch was ° s dered a really large amateur telescope, deep-sky objects of magnitude 13 ^C°emed like a realistic limit for most observers. But now, with 17-inch and larg-telescopes commonplace, many fainter galaxies that are not to be found in ular observing guides are accessible to amateurs.

^P A large telescope is not necessary to enjoy the pleasures of Crater, where the ity _of naked-eye stars makes good charts quite necessary; it is almost always indispensable to have an atlas showing stars to at least 9th magnitude.

Figure 6.11 Despite its southerly location, the egg-shaped galaxy NGC 3887 can be spotted in a 4-inch telescope near Zeta (£) Crateris.

There are perhaps a score of objects within the reach of an 8-inch under good skies. NGC 3887, an 11 th-magnitude spiral galaxy (Figure 6.11) not far from 5th-^magnitude Zeta (Q Crateris, was discovered by William Herschel. Its oval disk is about 2.5' long and rather easy to find in a region devoid of faint stars. In the mid-^s the galaxy showed well in a 4-inch f/16 off-axis reflector. In the transparent

V Kansas, a 10-inch f/8.6 reflector at 60x revealed NGC 3887 to be quite 8 t and egg-shaped. My old notes also suggest that a trace of the spiral arms ^as also visible in this instrument. The galaxy is easily picked up in my 5-inch P gee telescope, but at 20x it is a blur just barely distinguishable from a star.

NGC 3672 is another spiral galaxy discovered by the senior Herschel 1( • little brighter than 12th magnitude, and some 3.5' long and half as wide. [ _v: , '^{S a}this galaxy from Madison, Wisconsin, with the 6-inch Clark refractor that I belonged to the famous double-star observer Sherburne W. Burnham. My'm^ novice eye required 150x for the observation. One of this telescope's eyepj_e(,^Cnwas most unusual for its time; it was of l'A inches focal length, made by Jo^ Brashear, and possibly designed by Charles Hastings. It had a wide ap_pa ” field, and gave such unmatched views of deep-sky objects that it played a nt " role in my growing interest in this branch of observing.

NGC 3637 is a tiny spiral only about 1' in diameter. With low powers this object will almost always be mistaken for a star. I suggest searching for it with a least lOOx. There is a 7th-magnitude star just 3' southwest of the galaxy. Similar in shape and difficulty is the slightly smaller elliptical galaxy NGC 3732. Again high magnifications will be a help when searching for this object.

More challenging is the faint spiral galaxy NGC 3865. It was missed by the Herschels, and, not surprisingly, I have never been able to find it with my 4-inch Clark refractor. I have seen it, however, with the 20-inch Clark at Wesleyan University. Its oval disk is about 1.5' long and of magnitude 13.5 or perhaps a bit fainter.

If you are successful in locating NGC 3865 and want to try something even more challenging, try hunting down the twin galaxies NGC 3634 and NGC 3635, which are nearly in contact with each other. They are almost stellar in appearance and around 15th magnitude. If the sky is perfectly clear and dark, they may be within the reach of a 10-inch telescope at high magnification. A 16-inch should show these galaxies well above thc visual threshold.

Many amateurs living at mid-northern latitudes consider the southern constellation Corvus, the Crow, dim and uninspiring. But when I first saw it from Central America I found it far more impressive than Hercules. I often wonder why there is no indication of this star pattern in the Mayan Codex (of Mesoamerican astronomical tables); then again, maybe there is and scholars just haven't recognized it yet. Its four prominent 3rd-magnitude stars, however, do not remind me of a crow. I grew up on the shores of Lake Michigan where sailboats were part of my very essence, and I can see Corvus only as the sail of a small gaff-rigged vessel heading eastward on the back of Hydra.

The first telescopic object I usually turn to is the small but really fine planetary nebula NGC 4361, located in the north central part of the “sail ^! ig^urc6.12). Curiously this object was not included by Smyth in his Cycle of Celestial Objects, and William Herschel thought that it was resolvable into stars. This description is all thc more strange because even in my 4-inch refractor NGC 4361 looks like a planetary, and in a 12-inch its character is unmistakable. It is not a typ* ical planetary, however, for Lick Observatory photographs show a central nucleus with arms superficially resembling a barred spiral. If NGC 4361 were highei in _|hu. northern skv. I can t help but think that it would have ended up in Messier’s .,_lialog and thus be considered among the anointed by today's amateurs.

[t is wise to use at least 80x to lOOx on it. The total visual magnitude is about 10. so the surface brightness is about four times less than M57, the Ring Nebula in I yra-^{Its a}PP^ears larger than Jupiter. Its bright, inner core is about // across, but the outer halo approaches 2'. Careful observers have spotted it with binoculars, pbo 4-inch Clark refractor at 40x shows this planetary as a circular object filled with mottled light. At lOOx the mottling was pronounced and the central star, reported to be of 13th magnitude, was not seen with my left eye. My right eye, however, which had its ultraviolet absorbing lens removed in a cataract operation, showed the star to be at least a magnitude above the visual limit. (This, by the way, is exactly the same experience I had with the central star in the Ring Nebula.)

The hot star at the center of NGC 4361, whose ultraviolet radiation excites the nebula’s thin shell of gas to glow, had proved a challenge for me before mv cataract operation. I had failed to see it with my 4-inch Clark refractor — a telescope that routinely reaches stars of 15th magnitude. I attribute this to the lower

contrast between the central star and the nebula’s light than ii the star lay against a dark background. The planetary’s nebulous haze reduces contrast between the star and the background, and maximum contrast is essential to achieve optimum performance from a telescope.

Ronald Morales — an experienced observer of planetary nebulae examined 4361 with an 8-inch f/5 reflector and a range of eyepieces With a 10.2-mm ocular (lOOx) the object appeared "bright, round, diffuse with irregular ede> and the central star easily seen." A 16-mm eyepiece (64x) also showed the but a 25-mm (41x) revealed the planetary to be a "fuzzy patch with the star o *i suspected." It is worth remembering that deep-sky objects can often appe/ quite different when the same telescope is used at various magnifications fl/ fact that the seemingly small change from 41x to 61x would make the difference in the central star's visibility should serve as a vivid reminder.

When observing faint objects such as NGC 4361. take full advantage of dark adaptation and averted vision. Spending half an hour or more in darkness can add surprisingly to the visibility of faint detail.

Figure 6.13 A firestorm of starbirth activity was triggered by the collision of these two galaxies — NGC 4038 and 4039 — popularly known as the Ring-tail Galaxy or the Antennae.

NGC 4038, with its companion NGC 4039, is popularly known as the Ring-tail Galaxy or the Antennae (Figure 6.13). Located along the western edge of Corvus, it is listed as a peculiar galaxy, and that alone makes it a tempting target for amateur and professional astronomers alike. The unusual shape is believed to result from the collision of two galaxies, a theory borne out by computer simulations. Though Burnham devotes considerable space to this object m his Celestial Handbook, the visual observer will see only an asymmetrical blur, about 2¹/?' in diameter and 11 th magnitude. NGC 4038-39 is shaped like an apostrophe in my old 10-inch reflector. Photographs made with large telescopes show two separate central masses each with a long curving tail. This is a unique sigh* vvould be a good target at a star party, where it could be viewed in several different telescopes.

° Several times amateurs have sent descriptions of what they believe is this , but I’m sure they have mistaken another galaxy for the Ring-tail. My 5-7 . 20x Apogee refractor shows the pair as a bright blob. An observation made ^,n _h’ mv 4-inch Clark refractor under the indifferent skies of my old home in Haddam. Connecticut, revealed NGC 4038-39 to be little more than an asym-trical 1 lth-magnitude blur. However, at a campsite near Big Sur, California, I °iewed a wealth of detail in the Ring-tail with a borrowed 12-inch reflector. Other reports in my files support this. At Omaha. Nebraska, Frank Rolwicz’s 10-inch Newtonian easily showed the galaxy’s “tail.” And viewing with a 10-inch reflector. Morales thought that the galaxies looked like a shrimp.

What they remind me of, however, is heavily inspired by my interests while in ₂rade school. Even before I discovered telescopes, I was crazy about microscopes. 1 would talk my science teacher into letting me borrow the school’s microscope on holidays and weekends, and would bicycle to lakes and ponds near my home in Wisconsin to examine water samples. One creature I found in abundance was the water flea, Daphnia. There was a time when I could instantly identify a dozen species with just a glance in the microscope. So it’s understandable why I associated NGC 4038-39’s photographic appearance with the grandmother of all water fleas.

About 40' southwest of the Ring-tail is a galaxy of similar size, NGC 4027. I make its visual magnitude to be 11.3, about half a magnitude fainter than NGC 4038. Most telescopes will show both objects in the same low-power field.This spiral is about 2' in diameter and I have seen it in my 4-inch and in the Moonwatch 5-inch Apogee telescope. The background is so uncluttered in this area that faint nebulae are definitely easier to identify than in most other parts of the sky.

A pair of small galaxies in eastern Corvus is probably too faint for a 4-inch telescope, but should be within the grasp of an 8-inch. NGC 4782 and 4783 are almost touching each other. These twin elliptical galaxies are 0.5' across with photographic magnitudes of 12.9, but are a bit brighter visually. They lie about 14° due north of an 8th-magnitude star, and I suggest searching for them with a magnification of about lOOx.

■Bvo more galaxies are nearby. They are very faint, and I suspect they require at least a 12-inch telescope. Some 9' east of the last pair. NGC 4794 is about 14th magnitude and slightly brighter than NGC 4792 to its northwest. Experienced astrophotographers might find these galaxies a challenge. If so, I am sure your ^results will be worth the effort.

Before leaving the Corvus region, try examining M104, just over the northern fder in Virgo. Recall the earlier discussion of Messier’s original catalog of star asters and nebulae, published in Connaissance des temps. It had a total of 103 ^^tr'es, but Messier’s personal notes made it clear that he knew of other objects.

^r°ugh the efforts of 20th-century astronomers who studied the catalog in ^eta>l, these objects have been included as entries 104 to 110.

It was the French science popularizer Camille Flammarion who got the I rolling when, in 1921, he proposed that NGC 4594 be included as M104 beca Messier had penned a reference to the "nebula" in his own working copy _Of l ⁶catalog. ^Is

Figure 6.14 The Sombrero is one of the most easily recognized extragalactic deep-sky treasures. It lies about 65 million light-years away and is part of the great Virgo Cluster of Galaxies.

Often called the Sombrero Galaxy, M104 is an easy object for even the smallest telescope (Figure 6.14). Its bright, 8th-magnitude oval disk is about 8' long and well within the reach of binoculars. The nearly edge-on galaxy is noted for a dark band slicing across its middle. In their Observing Handbook and Catalogue of Deep-Sky Objects, Christian Luginbuhl and Brian Skiff note that "the dark lane can be seen easily" in a 6-inch telescope. On the other hand, John Mallas. the skilled deep-sky observer and coauthor of The Messier Album, could not see the lane with a 4-inch refractor.

But on one excellent night back home in Connecticut I saw the lane with a 4-inch Byrne refractor and a 4-inch off-axis reflector. To my surprise the lane was more difficult in the refractor, even though refractors usually scatter less light than reflectors. Scattered light degrades the view by reducing image contrast. When I placed a dark cloth over my head to block light entering my eye front the side, M104’s dark lane was definitely easier to see.

Sometimes it’s easy to forget just how much the atmospheric debris, which becomes more concentrated as we look near the horizon, affects our view of the sky. This is true whether we use the naked eye or a telescope. For me. many ^olthese southern objects would have much less appeal were it not for my occasional excursions into Central America, where they stand 20° higher than at home. I suspect that whenever eclipse chasers travel to southern locations, they find viewing the night sky just as rewarding as the solar three-ring circus itself-

Ast = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dark Nebulo; GC = Globular Cluster; Gx = Goloxy; OC = Open Cluster; PN = Planetary Nebulo; » = Star; * * = Double/Multiple Star; Var = Variable Star

Peering into the Cat's Eye

"Skies around the north ecliptic pole in Draco are rather barren," Scotty once wrote, • but a few interesting objects wait for the zealous observer." Take the bright planetary nebula NGC 6543, for example. Scotty believed that pale green planetary nebulae of its caliber were sometimes neglected by amateurs. It's easy to understand why. Some are so small they could be easily mistaken for stars. "When searching for one of these emeralds," Scotty advised, "the observer must first locate the field very carefully, and may have to examine many stars at higher power to discern the nebula's tiny disk." The Cat's Eye is different, however. Through a telescope it appears as a small bluish disk about the angular size of Jupiter, and looks like an out-of-focus 9th-magnitude star. It does offer special challenges to observers with all manner of observing aids. But, as Scotty attests, a glimpse of it through a large-aperture telescope can turn the purest scientist into a hopeless romantic.

You are all poets,” 1 told a gathering of amateur astronomers at the 1983 annual Texas Star Party. At first they reacted with silence. Then they began to agree. The common thread that binds amateurs together is a love of the grandeur and beauty of the starry deeps. While some may claim it’s the science of astronomy that interests them. I believe that deep down it is the ultimate experience of the night sky that holds the real attraction.

After my talk I received a letter from Christine Combs of Colleyville, Texas. “I ^Was introduced to NGC 6543 at the Texas Star Party.” she wrote. “The first sight ^was breathtaking... to see the bright inner star surrounded by greenish-blue neb-tilosity ... we observe with a 20-inch Dobsonian, usually with 200x. Last night I ^exPerienced anew the excitement of seeing this greenish cat eye buried deep in sky for me to wonder at. My husband, an engineer and long-time amateur. ^may give a more detailed description, but I'm the poet and always strive for words ⁰ describe the feeling aroused by these deep-sky wonders.”

The object that captured Combs's imagination is one of the most glorious plan-f^tary nebulae in the sky (Figure 7.1). Located in Draco. NGC 6543 lies only 10' ^Orn ^e ecliptic’s north pole.The ecliptic is the annual path of the Sun among the Figure 7.1 NGC 6543, the Cat's Eye (center) in Draco, is estimated to be 1,000 years old.

Its complex structure reveals the dynamics and late evolution of a dying star and its companion.

stars — a great circle on the sky, tipped 23/2° to the celestial equator. Thus NGC 6543 lies at the center of the circle traced by the Earth’s pole during its 26,000-year precessional wobble. Because of this unusual location, precession has little effect on the planetary’s right ascension and declination.

Combs’s remarks sent me hunting for my earliest observing records, made in grade school more than half a century ago. Sure enough, I had penned: ‘6543, which Astronomy with an Opera-Glass says is a planetary. I see a green star, but much wider than the other stars around it.” These notes describe views with a homemade 1-inch refractor at 40x. A larger instrument will easily reveal its nebular nature. My 4-inch Clark refractor shows it as a rather uniform bright disk about 20" in diameter, but high magnification reveals areas of irregular brightness. Photographs show the nebula has a coiled form similar to the much larger Helix Nebula in the constellation Aquarius. Its length is about 22". or two-thirds the separation between the components of the double star Beta (P) Cygni (Albireo).

NGC 6543 made a bit of astronomical history in the 1860s. Before then it was assumed that most nebulous objects were actually clusters of very faint stars, and a failure to see them as such was merely due to lack of a big enough telescope. NGC 6543 was one of these unresolved objects. Then, on August 29. 1864, William Huggins turned an 8-inch refractor equipped with a visual spectroscope toward the nebula. (He was the first person to turn a spectroscope toward a planetary nebula.) Rather than a continuous streak of light spanning the visible spectrum, Huggins discovered that the spectrum of NGC 6543 consisted of three bright lines, the strongest being in the green. Thus, “at a glance” he realized that NGC 6543 was a cloud of luminous gas and not, as some astronomers had

•ill deep-sky objects arc made of stars.The mysterious green lines were attrib-^111,1 | to a hypothetical element called nebulium. More than half a century would ^llU before these lines were recognized as due to doubly ionized oxygen. ^fjGC 6543 ^{offers several} challenges for the observer. One concerns the nebu-• color, and another the brightness of its central star.Through his obervations, William H. Smyth found the planetary a "very fine pale blue," while other bservers have seen it more as green. Smyth seems to have had an unusually °cute sensitivity for color; most amateurs today cannot distinguish the multitude _of shades he could. 1 suggest using a magnification of about lOOx when making color estimates.

NGC 6543’s central star shines at about magnitude 11, but the interior stars of planetarics arc more difficult to see than their magnitudes suggest. That the central star is surrounded by bright nebulosity means there exists a contrast effect, which poses a problem when attempting to judge the star’s brightness. Modern catalogs generally list 9.5 as the visual magnitude of the star. However, my own estimates tend to favor a fainter value. The central star is also bright when compared with other planetaries. With a 3- or 4-inch telescope at 30x, NGC 6543 may look like little more than a swollen star, but as Combs’s letter testifies, with a large instrument the nebula can be very impressive.

I recently hunted up NGC 6543 with my 4-inch Clark refractor. At 120x the view with my normal eye showed the planetary and its central star much as expected. With the other eye, which had its lens removed during a cataract operation, the star was brighter than the nebula! This was due no doubt to much more ultraviolet light from the hot star reaching the retina of my lcnsless eye. Deep photographs record a faint shell about 4' across surrounding the planetary, but I doubt it can be seen visually.

In 1985 I asked for reports from amateurs who examined NGC 6543 with large telescopes. One such report came from Michael Gardner of Sunnyvale, California. As a member of the Mount Wilson Observatory Association, he had viewed it with the observatory’s 60-inch reflector! It was a particularly good night, as fog had rolled into the Los Angeles basin and obscured the city lights. Furthermore, 'he fine seeing for which Mount Wilson is so noted was even better than usual.

We were observing at the Cassegrain focus of the 60-inch,” Gardner writes. “A 55-nun Plossl produced 450 power and a field of view about 6/2' in diameter. NGC ^543 was a stunning blue-green oval. The colors were like a Kodachrome. We saw ^much more structure in the planetary than the picture [S£y & Telescope, July 1985, P^agc 89] shows, and the colors were much more vivid and bluish." Gardner did not $^{ee l}^^e faint shell about 4' across that surrounds the nebula on deep photographs, ^Ul h^e was not specifically looking for it.

Often planetary nebulae will show best within a very narrow range of magnifi-^atlOn for a given telescope. Once you have located one of these glows, spend ^e time experimenting with different eyepieces (don’t forget to try a Barlow lens if you have one). Aperture masks may also improve the view. Careful exam ination of an object can sometimes reveal details not generally noted in observ ing handbooks. For example, while viewing NGC 6543 I found the central star "blazing yellow," due to its strong contrast with the nebula's blue color. I do not recall ever reading about this effect before.

The Crown Jewels

Observing is a continual learning experience. At first, time spent under crystalline starlight has all the flush and romance of a soft embrace on a warm summer's eve Wasn't that first glimpse through a telescope enchanting? As we grow and become more knowledgeable, we tend to move past the romance and begin to challenge ourselves and our visual limits. We start first with the naked eye and binoculars, then move on to modest-sized instruments, until we find ourselves delving ever deeper into the universe with ever larger telescopes. Once we have years of experience under our belts, we start seeking out celestial treasures that seemed impossible when we first started out. For more than four decades Scotty watched amateur astronomy progress in this way, as if our visible horizons and telescope technology were expanding in sync with the universe. Here Scotty shows how one of the sky's smallest constellations, Corona Borealis, can satisfy both the naked-eye novice and the monster-telescope owner.

The stars are always with us. Night after night the blaze of distant suns stretches from horizon to horizon. For many of us the fascination of a starry sky began even before grade school, as the spectacle of the heavens astonished and excited our imagination. As we tally more and more memorable hours under the night sky, the sensation is cumulative. It makes no difference whether we observe with the naked eye, a 4-inch telescope, or a 36-inch Dobsonian.

With each passing year the parchment of the sky comes to hold more information, more contentment, and more wisdom for us. We know that as we step out under the stars tonight we will be headed for a reunion with some old friends. Nevertheless, as observers we must be prepared to push beyond our accepted frontiers, perhaps even to the point of having to reject some “truths" to which we have devotedly clung.

As darkness falls on July evenings, one frontier I always turn to is Corona Borealis, the Northern Crown. The constellation rides high in the sky, aloof front the fainter stars of Bootes and Hercules. This ancient group is one of the few star patterns that span many cultures in essentially the same form.

Two objects in Corona Borealis are of special interest to naked-eye observers. Both are variable stars, but they have very different behaviors. R Coronae Borealis (Figure 7.2) is usually 6th magnitude and just visible to the naked eye under good conditions. It remains relatively constant, sometimes for years; then it can abruptly plunge to around 14th magnitude. Recovery is often slow, and

here ca^{n man}y relapses. Sometimes the star takes several years to regain its filial brightness. I check the naked-eye visibility of R Coronac Borealis every *|car night — if it's missing, out comes the telescope.

Sonic 3° to the southeast is another interesting variable. Unlike R Coronae gorealis. this one attracts the most attention tv/ten it attains naked-eye visibility. T Coronae Borealis is a recurrent nova and typically hovers around 10th magnitude. p_ut it has exploded to 2nd or 3rd magnitude. This happened in 1866 and 1946, and lesser flare-ups occurred as recently as 1963 and 1975.The next burst will likely be first spotted by an amateur who checks T Coronae Borealis with the naked eye or binoculars.

On the other end of the spectrum, the explosive growth of amateur astronomy has produced an interesting group of specialists — those who delve into the deepest of deep skies. While such people don't lend themselves to easy description, I've pieced together a rough profile based on my mail. They are individuals who observe alone. They use at least a 12-inch telescope, more typically a 17-inch or larger instrument.They are experts at getting the most from their telescopes. They keep the optics as clean as possible to reduce the scattered light that dilutes the contrast between a faint object and the sky background.They also make proficient use of the various nebula filters currently on the market.

Objects in the New General Catalogue of Nebulae and Clusters of Stars (NGC) are ^Slr>all potatoes to these people. The NGC objects were discovered visually in the 19th ^Ceniury. so they lack the attraction of fainter quarry — objects that were likely discovered on photographs and many of which have never before been viewed direct ly! The popular observing guides are therefore of little use. Instead these observers turn to multi-volume catalogues with such alien code names as thc UGC, MCG, and MOL*, which are usually found only in professional observatories.

These observers make up only a tiny percentage of amateurs. Most of us p_refer a casual stroll through the well-tended gardens of the heavens as opposed to beating new trails through thc dense celestial jungle. But every now and then it’_sfun to take on a challenge — to climb a difficult path and stand for a moment on a mountain peak.

The Corona Borealis cluster is a rich swarm of galaxies 940 million light-years distant. Observers who search it out will be rewarded with the sight of dozens of tiny gray spindles scattered across the deeps.

For instance, take veteran deep-sky observer Ronald Morales, who described his quest for the faint Corona Borealis galaxy cluster (Figure 7.3) in the May 1990 issue of Sky & Telescope (page 563). Morales explained how he keeps a “failed-to-see” list of objects that he returns to on nights when the sky is unusually dark and transparent. By doing this he has located many that he might otherwise have given up hope of finding — objects that have brought him unexpected pleasures. This is a worthwhile practice for every serious deep-sky observer, but I can’t recall ever seeing it in print before.

The Uppsala General Catalogue of Galaxies, the Morphological Catalogue of Galaxies, and the Master Optical List of Nonstellar Astronomical Objects, respectively.

Morales’s name is familiar to many readers. In addition to his own articles, I ! mentioned his observations many times in this column. He has an observa-*’^aV _olltside Tucson. Arizona, that includes telescopes with apertures up to 17%. ? hes but his favorite is a 12%-inch f/7 Cave reflector. Many years back Morales E. I spent ^{an evenin}S observing with his 8-inch reflector under the pristine ^al'\ of Arizona’s Empire Mountains. That night I had my best view ever of the ^S bulosity surrounding thc Pleiades. Morales is also coauthor of the Webb Society Deep-Sky Observer's Handbook, Vol. 6: Anonymous Galaxies, a source _of endless deep-sky challenges.

Dueling Globulars

-The northern winter sky," Scotty wrote, "sparkles with scores of open clusters that dot the Milky Way. Spring brings the realm of galaxies into view, and autumn is for hunting planetaries. But it's the warm summer nights now upon us that are perfect for viewing globular clusters." In fact, if you look at the meridian in mid-July around 9 p.m. with the naked eye and binoculars, you can spot several Messier globulars lined up from north to south, as if clinging to some sinuous celestial vine. In order, they are M92 and M13 in Hercules; M12, M10, and Ml07 in Ophiuchus; and M80 and M4 in Scorpius. A little tilt of the head east or west will bring others into view: M5 in Serpens; and M14, Ml 9, and M62 in Ophiuchus. A telescope will reveal even more globular wonders. What to do? Which ones to cover? Well, without question, the most popular globular is M13 in Hercules. But Scotty was hesitant to bestow full honors on it, for — as we next read — it appears he preferred another globular over this one.

As you read this, amateurs somewhere are looking at the splendid globular star cluster Ml3 in Hercules (Figure 7.4). Some might be comparing notes on how well various telescopes resolve the cluster into individual stars. Others are using it as a test of eyesight or sky conditions (though with a total magnitude °f 5.9, this ball of ancient stars should not be much of a challenge except from Places like the fens of southern Connecticut). M13, along with the Orion Nebula, ^,s perhaps the most frequently observed deep-sky object. Indeed, even when Halley's Comet beckoned people to look skyward during 1986. it is probably fair to suggest that more people saw M13 than thc comet itself. It is pure coincidence, '^1ut nevertheless interesting, that Edmond Halley chanced upon M13 in 1714. following year he published a paper that was the first to describe a half ^ozen “nebulous” objects in detail rather than mention them as asides to a star catalog. Of the great globular Halley wrote, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.”

I*¹ J^Une 1986 I mentioned that MB’s popularity is derived not only from its ^s'^Ze and naked-eye brightness, but also from its favorable sky location. For ^ervers at mid-northern latitudes the cluster is visible much of the year. On

The great globular cluster Ml 3 contains more than 100,000 stars to 21st magnitude. The true stellar population may be close to half a million.

pleasantly warm summer evenings it passes nearly overhead where the view is through the thinnest layer of interfering atmosphere. Furthermore. M13 is conveniently placed on the line between Eta (rj) and Zeta (Q Herculis, which forms the west side of the Hercules Keystone. With such prominent stars to point the way, it’s easy to understand why even novice observers can quickly locate the cluster. M13’s association with the Keystone is so interwoven that the relatively small asterism is believed by many to be all there is to the constellation.

Small binoculars or a finder will show M13 as a pale, colorless glow with a diameter as much as half that of the Moon. If encountered accidentally while sweeping, M13 can be quite startling. A 3-inch telescope will just begin to show stars at the cluster’s edge, and a 4-inch will add more. The fact that Charles Messier never saw any with his 60x Newtonian of 4!4-foot focal length shows just how far telescope making has advanced in two centuries.

By the mid-1800s. W. H. Smyth was extolling MB’s appearance in a 5.9-inch refractor. “An extensive and magnificent mass of stars,” he wrote in 1844. "with the most compressed part densely compacted and wedged together under unknown laws of aggregation.” Smyth had read a similar comment by Wiilia⁰¹Herschel, and this may have influenced his own observations.

Photographs, too, have influenced observers, but not always in a positive way-About 1850, while using Lord Rosse’s telescopes in Ireland, Bindon Stoney

,j _an unusual pattern of three dark rifts (Figure 7.5) radiating outward from ^lU’n the center of M13.The 19th-century observer and author Thomas W. Webb ⁿ ntions in his classic Celestial Objects for Common Telescopes that these lanes ¹¹¹ “beautifully seen by Buffham,” who used a 9-inch reflector.

afterward photography became the all-powerful tool of astronomy, lion of Stoney’s rifts essentially disappeared from the literature. I suspect 'cause the lanes did not appear on early photographs of M13. I first wrote bout the "propeller" in the July 1953 column, but no amateurs of the day orted seeing it. Every few years I would bring it up again, with similar results. It wasn’t until 1980. after I asked several more times for amateurs to hunt for them that John Borllc reported seeing the lanes with his 12/;-inch Newtonian reflector at 176x.The cosmic jest surrounding the sighting was that Bortle, tired _of reading about the folklore of the lanes in my column, set out to disprove their existence, or so he said in his letter. Sighting the lanes seems to depend upon a careful balance of aperture and magnification. Both Bortle and Dennis di Cicco commented on the importance of magnification. During the Stellafane convention in 1981, di Cicco was surprised by how easily the lanes were seen with the 12-inch f/17 Porter turret telescope at about 180x. However, even knowing their orientation and appearance, he was unable to see them at 95x with a 12-inch reflector that was set up nearby.

Jan Romer of the Delaware Valley Amateur Astronomical Association in Pennsylvania reports that he cannot see the lanes under any conditions with an

In this negative drawing depicting Ml 3 by Lord Rosse, three lines form what looks like a dark propeller near the core of globular cluster Ml3.

8-inch f/8 reflector at lOOx. He does see, however, many star chains crossing th_ecluster and also several of the star-poor areas mentioned by observer and write_rJohn Mallas. Most observers note that they appear best at magnifications _Of about 200x. It is exciting to think that these lanes can again be seen after a lap_Seof nearly a century in which no one reported viewing them. The feature is off_Selto the southeast edge of the cluster.

Veteran observer Mark K. Stein may hold the record. He writes, “When I lived under the polluted skies of Louisville, I considered some of your descriptions of deep-sky objects the result of a fine, experienced observer having a slightly overactive imagination. But now in the much darker skies of Bloomington, 1 can plainly see objects I wouldn’t have attempted from Louisville.” With a 6-inch at his new location Stein has seen the dark lanes in the globular cluster M13. This feat puts him in a special class, for the lanes usually require an 8-inch or, better, a 20-inch. I have never seen them in my 4-inch Clark — but I keep on trying.

On long-exposure photographs the myriad stars in M13 spread out to a diameter of more than 20', two-thirds of the Moon’s diameter. In a 4-inch telescope only the cluster’s edge can be resolved. A 10-inch instrument, however, will show more stars than the eye can count, though the center still remains a solid glow. Sharp-sighted amateurs will notice that M13 is not circular as it appears in long-exposure photographs. Early drawings like Lord Rosse’s show dark lanes and strings of stars — all still apparent to the visual observer. Of course, the resolution of M13 depends somewhat on magnification. An 8-inch aperture at 30x will not separate the stars because the cluster’s core appears too bright. Increasing the power to 300x, however, reveals stars across the entire field. One of my most memorable views occurred when a smog layer had reduced the naked-eye magnitude limit to about 4/2. As is often the case, the seeing was very steady then. At 300x the cluster was faint, but the individual stars stood out well. The number of stars attributed to the cluster depends upon which reference you consult, but all agree that it runs well past 100,000.

Every deep-sky observer has a list of favorites: a planetary nebula, a test object for sky transparency, or a special area of the heavens to sweep on nights when the conditions are just right. One of my pet objects is well placed in the July evening skies, near the border between Virgo and Serpens — the remarkable globular cluster M5. Formerly M5 was included in an extension oi Libra which curled up into Serpens, and consequently it is catalogued as a Libra object in the older observers’ texts, by Smyth, Webb, George F. Chambers, and Garrett P. Serviss. Since the I AU revisions of the constellation boundaries, it has otiicial-ly been charted in Serpens (Caput).

The German astronomer Gottfried Kirch found M5 in 1702. Messier, with a very small telescope, described it as a nebula. Smyth wrote: “This superb object is a noble mass, refreshing to the senses after searching for faint objects: with

utliers in all directions, and a bright central blaze which even exceeds M3 in ncentration.” It lies at the eastern end of a short chain of three, faint, naked-^C stars: 109 and 110 Virginis and 5 Serpentis. M5 is just 0.4° northwest of 5 Serpentis and is almost Z° in diameter (Figure 7.6). I saw it with my naked eye under the clear skies of Arizona, as well as from the summit of Temple I at the Mayan ruins of Tikal in Guatemala.

Telescopically M5 is a treasure house, and every increase in aperture brings _new sights. With low power on a small instrument it is very beautiful and bright, but not resolved. Its appearance is comparable to that of M13 in Hercules. At home in Connecticut, my 4-inch Clark refractor shows the cluster with a lacy fringe of stars. Years ago a 10-inch reflector in Kansas revealed some 300 stars, and the background glow hinted at

tor at Wesleyan University, I would add that M5 seemed more like a starry blizzard.

The English observer Kenneth Glyn Jones contended that M5 is second only ^to M13 in the northern hemisphere. But it may come as a surprise to learn that M5 is actually listed as being a tenth of a magnitude brighter (5.75 versus 5.86) ^ln Sky Catalogue 2000.0. Both Ml3 and M5 are of similar size, too. In fact, M5 is the brightest globular cluster in the northern hemisphere of the sky and indeed ^ls surpassed by only two southern globulars, 47 TUcanae and Omega Centauri.

^e there times when you can see M13 and not M5 with the naked eye? It would ^an tnteresting project to see what the effects of altitude have on each object. ^niay he that M13 is the better-known cluster only because it passes nearly °^Verhead for those living at temperate northern latitudes.

The Orphans of Ophiuchus

Warm summer nights in July offer us the richest regions of the Milky Way. Under a dark sky, its smoky trail of fused starlight is dappled with the hazy light of globul clusters. Not surprisingly, Ophiuchus, the sky's 11 th-largest constellation (in area) contains a plethora of these objects, including a half-dozen that belong to Messier's catalog: M9, M10, M12, M19, M62, and M107. Naturally, beginners tend to explore the Messier objects first. But Ophiuchus has a host of lesser-known sights worth scouting out. Furthermore, Scotty alerted those with wide-field telescopes to be on the lookout for the sinuous veins of dark nebulosity that empty into black lagoons of obscuring dust near many of the Ophiuchus globulars. "There is something for everyone," Scotty wrote. "Fine objects abound, and the central part of Ophiuchus, lying between the two sections of Serpens, provides a test for the observing capabilities of amateurs with modest-sized telescopes." Indeed, the Serpent Bearer is full of celestial surprises, as we shall see.

Some joys of astronomy are seldom mentioned. There is the pleasure of sifting through a musty 19th-century book with its quaint prose, knowing that it inspired countless people to look at the heavens. Hidden among the pages of another is a fine engraving of an old telescope that, carefully examined, yields ideas for today’s telescope makers. Old atlases show interesting constellation figures and star names. While many of us enjoy old books and charts, we also delight in works of recent vintage. It is all as much a part of amateur astronomy as looking through a telescope on a July evening.

Perhaps the best-known contemporary celestial cartographer is Wil Tirion of the Netherlands. In recent years his beautiful star atlases have been widely circulated. Let’s consider for a moment the right-hand half of chart 22 in the deluxe version of Sky Atlas 2000.0. Scorpius sprawls across the field as it unwinds from brilliant Antares, the Scorpion's heart — to Shaula, the stinger in its tail. For those of us living in the northern United States, the southernmost stars on this chart are, at best, difficult to see. Still, we are better off than amateurs in Canada, England, and even at the latitude of Messier’s Paris, since a good portion of the heavens charted here never rises above their southern skyline.

The Milky Way here cascades down the sky as indicated by the shades ot blue on the chart. The dust in our own galaxy blocks the view beyond, so the familiar red ovals of external galaxies are lacking from this section of Tirion s chart. However, other interesting features of the sky are apparent. The galactic equator, representing the plane of the Milky Way, rises steeply through the field. To its east is a profusion of open clusters, shown in yellow, but few lie to its west. North of Antares, especially in Ophiuchus, stars are remarkably scarce; in many places it is possible to draw a 2° circle that doesn't contain a single star down to the 8th-magnitude limit of thc chart. Yet on the other hand-the star-poor region of Ophiuchus east of Antares contains an abundance of

0ne example is the open cluster IC 4756 in the eastern half of Serpens (Cauda). It is one of the largest such objects in thc heavens, appearing more than 1° across and just a little smaller than the Beehive cluster, M44, in Cancer. Some 80 stars between 7th and 12th magnitude are evenly scattered across IC 4756’s diameter. The Herschels probably missed it because the small fields of their reflectors would have passed right over the group without revealing any concentration of stars. IC 4756 appears as a patch of the Milky Way to the unaided eye. Binoculars or a finder will easily reveal its individual stars. While large reflectors will not show the entire object at once, they will be useful when searching for unusual star chains or dark lanes.

Many years ago Glen Chaple, Jr., of Townsend, Massachusetts, “discovered” a deep-sky object in Ophiuchus; he found about two dozen stars forming a group which could be glimpsed with the naked eye. He likened the cluster to the Praesepe in Cancer, but it was not plotted on his copy of Norton's Star Atlas.The object does, however, have a name. It is IC 4665 and is listed in the Index Catalogue to the NGC. In those days of stargazing, serious deep-sky observers soon learned that no single atlas can suit all their needs. Today, of course, IC 4665 is plotted on most modern star charts.

About 1° northeast of 3rd-magnitude Nu (v) Ophiuchi is the tiny globular NGC 6517. Only 4.3 ' across and about 12th magnitude, it usually requires an 8-^or 10-inch telescope to positively identify this cluster. However, last year, working with a finder chart that was plotted from thc AAVSO Star Atlas, I was able to locate NGC 6517 with my 4-inch Clark refractor at 150x. Lower powers made ¹¹ impossible to distinguish the cluster from a faint field star.

Some 1° northeast of NGC 6517 is the 5th-magnitude starTau (t) Ophiuchi. Continuing on a straight line for 1° more brings us to NGC 6539, another glob-^U'^ar missed by the Herschels. Of roughly 12th magnitude and 2¹/?' across, it is a ^challenge for apertures less than 8 inches. My notes contain only sightings made a 10-inch reflector. And, although I considered NGC 6539 a difficult object . y^ears ago, I know that during the last decade many amateurs have observed ^W|,li telescopes as small as 8 inches.

Io ^<^^not’^lcr difficult globular is NGC 6535 in Serpens (Cauda). It, too, was over-°°ked by the Herschels. Discovered in the 19th century by the English observer John Russell Hind, it is only about I/2' in diameter and 11th magnitude. my notes made years ago in Kansas read “at least lOOx needed to establish iderT tity as a globular,” in England. D. Bl anchett, using a 3-inch aperture, found Nc 6535 to be a “faint, elusive object.”

Tiny globulars seem to flourish in this part of the sky. Without suitable fi_n<j stars it is often extremely difficult to hunt down these challenging objects 0^ exception is NGC 6366. Locating it is easy, since it is in the same field as 5th magnitude 47 Ophiuchi, which lies 17' due west of the cluster. With magnifi_ctions of around lOOx. the 4-inch Clark shows NGC 6366 to be magnitude U 5 and some 3' in diameter. It cannot be recognized as a cluster at 20x in my 5-inch Apogee telescope. At Wesleyan University’s Van Vleck Observatory j_nMiddletown, Connecticut, I have used the 20-inch Clark refractor to view NGC 6366. It shows the object as some 5' across and looking more like a compressed open cluster than a globular.

Figure 7.7 The globular cluster M9 in Ophiuchus lies 30,000 light-years away, close to the center of our Milky Way galaxy. It is accompanied by the inky dark nebula Barnard 64.

Eastward in Ophiuchus is the globular M9, discovered by Messier in May of 1764. About 6' across and 8th magnitude, it stands out well against the background stars of the surrounding Milky Way (Figure 7.7). Hans Vehrenberg comments in his Atlas of Deep-Sky Splendors that with a small telescope M9 can be mistaken for a star. This is worth checking out. The cluster is near the northeast edge of a remarkable dark nebula. Barnard 64, less than '/2⁰ west oi it. With my 4-inch Clark refractor or 5-inch Apogee telescope the dark nebula is easily seen.

Most dark nebulae are difficult to “see," but here the rich background is rather uniform, and it is interesting to compare the star densities northeast and south east of M9. Try powers of about lOOx. These dark patches really show best on _tographs, and it was with photography that E. E. Barnard discovered most of ?ern earlier ^{this ccntury}'

^There are ^two gl°t^>u'^{ars on,}y ^a short hop from M9. About P/2⁰ to the north-t is NGC 6356. Although still in a rich star field, this 9th-magnitude cluster, 2' ⁶⁸ oss. is easy to identify, especially at higher magnifications. The other globular, mCC 6342, lies the same distance south and slightly cast of M9.This is more difficult only 0.5' in diameter and 10th magnitude. However, Canadian Pat Brennan notes NGC 6342 as "faint" but readily seen in a transparent sky. Northeast of NGC 6342 is another dark nebula, Barnard 259. It is not as sharply j_efined as Barnard 64 but still the stars should appear noticeably thinner here than in surrounding areas.

While checking my files I was amazed to discover that I have never written about the globular cluster M19 in Ophiuchus during the four decades of prcpar-i_no this column. It lies at about the same declination as brilliant Antares and 7/2° east of the Scorpion’s heart. The fact that Messier discovered this cluster while scanning the sky from Paris is a tribute to his observing skill. Even from the northern United States, where the cluster climbs nearly 10° higher in the sky than at Paris, M19 is not especially well placed for viewing.

John Mallas, whose location in Southern California was more suitable for examining M19, once remarked that the globular is a miniature of the great Omega Centauri cluster. M19 is 5' in diameter and a bright 6.6 magnitude. Under good skies it is easily seen in most telescope finders. The visual diameters of globular clusters depend to some extent on the size of telescope and the observer’s eyesight. Members of an observing group should compare their individual estimates of these objects’ sizes, using a micrometer, an ocular grid or reticle, or by timing transits over a crosshair in the eyepiece. The results may well be quite different for telescopes of different sizes. Similarly, apparent magnitudes may differ in large and small instruments.

Two other globulars lie within a short distance of M19. A little less than 2° east and slightly south is NGC 6293. You'll know you're headed in the right direction when you pass a 6th-magnitude star about 1° from M19. Just southwest of this star is the Cepheid variable BF Ophiuchi, which ranges between magnitude 7.5 and 8.5 during a four-day cycle. About 2' across and of magnitude 8.4, NGC 6293 can be seen with only a 2-inch aperture and shows nicely in 4- to 8-inch telescopes. And south and east of NGC 6293 are more great clouds of obscuring Material which reveal themselves primarily to the camera. However, those using l^arge-aperture, rich-field telescopes may be able to detect some of the more sharply defined boundaries here. Now return to M19. Just I/2⁰ north-northeast h is NGC 6284. It is a bit smaller and fainter than NGC 6293, but still suitable f°^{r sm}all telescopes. It is a nice cluster for beginners and searching for it provides good experience in hunting out challenging objects. Amateurs who have successfully worked down from the brighter globulars to such faint ones can feel ^Weh satisfied with their observing prowess.

More Surprises in the Serpent Bearer

Although Ophiuchus is best known for its profusion of globular clusters, few rea|j_zthat the Serpent Bearer contains a wealth of planetary nebulae that can both delig^ and test the mettle of all observers. When summer nights fall upon us we naturally tend to turn our telescopes to the more famous summer planetary nebulae M57 (the Ring) and M27 (the Dumbbell), which are climbing toward the meridian after sunset. But Scotty enjoyed the challenge of dim planetaries, too. He knew how difficult it was to confirm a sighting, especially if the planetary was small and faint and the atmosphere even slightly unstable. Under such conditions stars and planetaries look the same — like tiny swollen disks. Without access to a special star chart or photograph that shows an object in its precise position relative to nearby faint stars, observers can be at a loss. So how is one to know the difference between the two? For Scotty's readers, one way was to turn to the Deep-Sky Wonders column and find out how other observers worked out this dilemma. Another way was to look at a lot of planetaries. Fortunately, the wide area of Ophiuchus contains a variety of bright ones to help train your eye to recognize these gems.

Ernst J. Hartung’s book Astronomical Objects for Southern Telescopes contains a useful suggestion for observers of difficult planetary nebulae: hold a small direct-vision spectroscope between your eye and the telescope ocular. The prism spreads each star in the field into a narrow, faint streak. But because the visible light of a planetary nebula consists mainly of a close pair of bright lines in the green part of the spectrum, the nebula’s image remains almost entirely unchanged.

In this way, even the tiny faint planetaries can easily be picked out in a crowded star field, and Hartung had much success with objects only an arcsecond or so in diameter. While this powerful technique is not new, few amateurs seem to know of it. It is well worth trying, for the effect is startling. Here is a sample of brighter planetaries in Ophiuchus, some of which are readily recognizable by ordinary viewing, while others require the visual spectroscopic method.

NGC 6369 is one of the easier kind. It is within thc reach of all but the smallest telescopes. This lOth-magnitude object lies in a sparse field, facilitating its identification. It is a perfect smoke ring about half the apparent diameter of Jupiter. Several nearby naked-eye stars help guide the way. Ron Morales m Arizona saw NGC 6369 with a 10-inch reflector at 87x as "round, green, and with the edge quite sharp.” By using a magnification of 137x he could easily make out the nebula’s dark center.

Near the eastern edge of Ophiuchus is a small V-shaped asterism known as Taurus Poniatovii (the Bull of Poniatowski). Named for an 18th-century Polish king, this obsolete constellation contains the famous double star 70 Ophiuchi- a binary with an 88-year orbital period. In 1989, the 4.3 and 6.0-magnitude com ponents were near a minimum separation of 1.5". A few degrees to the northeast _this group, on the shoulder of the Bull, is the planetary nebula NGC 6572. Vilhelm Struve, who discovered this nebula in 1825, considered it to be one of “most curious objects in the heavens.”

''"in 15 ^x ^5 binoculars NGC 6572 appears as a star, if one knows where to look, jeed the nebula is a mere 16" in diameter, and could be mistaken for a star if y'wer magnifications were used even in a telescope. Yet with only a little power

The planetary’s central star is not difficult. Estimates of its magnitude range from brighter than 10th to less than 12th. but such are the problems when trying to estimate a star’s magnitude when it appears against a bright background. There are several reports of the star not being seen with 10-inch instruments. If you search for it, remember to use the highest magnification your telescope and the night will allow. This dims the nebula’s glow and improves the contrast between it and the star. A little over 3° north-northeast of NGC 6572 is the planetary PK 38+12.1 (Cannon 3-1), which is plotted on Tirion’s charts. Once located it is fairly easy to observe its 6"-diameter, 12th-magnitude disk. It is easy to find with the spectroscopic method (described above).

Certainly within reach of a 5-inch is the planetary NGC 6309. This 11.7-mag-nitude object is a bit more than 20" long and only half as wide. Ron Morales calls this the "Box Nebula” and reports a curious gray-green color seen with a 10-inch reflector. The English observer Ed S. Barker’s description in the Webb Society handbook for nebulae mentions NGC 6309 as appearing “slightly mottled” in an 8/2-inch telescope. He also finds a faint star at each end of the nebula. What do you see?

Finally. I must share with you a letter 1 received from Canadian amateur Dunstan Pasterfield, who had an interesting idea. During his first nights of observing, he scanned the sky with binoculars and was impressed with the large, very loose open cluster NGC 6633. (Webb's Celestial Objects for Common Telescopes lists this cluster in Serpens, but today we find it in Ophiuchus, according to the official constellation borders established in 1930.) When Pasterfield got an 8-inch reflector he immediately turned to NGC 6633. It s a lovely, great, straggling thing ... of an absurd shape," he writes. “I keep ⁿⁱy eye on it annually. I’m convinced that some day something will happen in ^my’ cluster.”

^s an interesting concept: adopt a deep-sky object and learn it so well that y°^u would know at a glance if something were unusual, like a nova or stray aster-^0|d or comet in thc field. The idea is not new. Robert Evans in Australia has ^rriorized hundreds of galaxies as part of his search for supernovae, and his

But you don’t have to learn hundreds of objects. In 1979 Maryland amate Gus E. Johnson was making his annual inspection of galaxies in Virgo when h" noted that M100 didn't look right.The reason was a 12th-magnitude supernov* and the credit for the discovery went to Johnson.

Naked-eye Globular Clusters

July 1994 was a sad month for Deep-Sky Wonders readers, because it was the last time Scotty's words would appear as such in the magazine. Scotty had died the previous December 23rd, while touring Mexico. His final column is reprinted here in its entirety, and revisits some objects discussed earlier in this chapter that were particular favorites. For this installment, Scotty wrote, "Astronomy, as I have known it since about 1922, is full of encouraging surprises. Share them with me." Funny how his last offer could as easily have been his first. His life seemed to have come full circle. And as this book testifies, Scotty's spirit remains with us, and his words will continue to inspire and teach us. Besides, the measure of greatness does not end with one's life, but continues as long as one's words or accomplishments continue to affect the lives of others.

V V back and scan the ghostly band of the Milky Way and its environs, see how many globular clusters you can detect with the unaided eye. If you observe from mid-northern latitudes and can detect 6.5-magnitude stars, there are eight globulars to try for this month in the evening sky: M2 in Aquarius, M3 in Canes Venatici, M4 in Scorpius, M5 in Serpens (Caput), M13 and M92 in Hercules, M15 in Pegasus, and M22 in Sagittarius.

It’s not unreasonable to place the naked-eye limit at magnitude 6.5.1 make no claim for special powers when my logbook shows I’ve gone that faint, or on special nights, a magnitude fainter! The rub is that globulars are not stellar points; their light is spread over a tiny area of sky — enough to make them a real visual challenge without optical aid.

I’ll assume that 6th-magnitude M13, isolated between the stars marking the western edge of the Keystone of Hercules, is no real contest; many observers regularly use it as a test of the night’s clarity. Instead, let’s begin with M5. since my records show that amateurs have not paid much attention to this celestial splendor. Shining at magnitude 5.7 and measuring 17.4' across, this globular is easy to find; just look northwest of the star 5 Serpentis, which M5 all but hugs-You’ll have trouble, however, if you can’t differentiate the cluster from the star-

German astronomer Gottfried Kirch first sighted M5 while hunting *°^rcomets in 1702. Charles Messier rediscovered it through the Paris smog si* decades later, describing it as a “fine nebula which I am sure contains no star-■ cluster remained unresolved until Siam Herschel trained his Zscopeonitinl791.My 4 inch Clark shows lacv edge of stars

_ders. The 20-inch Clark refractor _of Van Vleck Observatory in Middletown. Connecticut, transforms it ' into a dazzling mass of sparkling stardust. It is a shame to let such a brilliant summer object wither on the vine.

nitude M4 — a huge globular measuring 26.3' wide (Figure 7.8). While traveling through Central America, I spent many hours looking at M4 with the naked eye, binoculars, and my portable 4-inch rich-field reflector. I have seen it from the wild Peten jungle of Guatemala and at midnight from the top of the pyramids in the old city of Tikal. Always it has been rewarding. To see it with the naked eye, you must filter out the “glare” from brilliant Antares, though this is not difficult from the darkest of sites.

Through a telescope M4 is a dynamic object. Although Webb, in his Celestial Objects for Common Telescopes, refers to it as being “rather dim,” remember he viewed it from high-northern latitudes. From the Florida Keys, where the Winter Star Party is held, the huge ball of M4 is mighty impressive. While you’re in the vicinity, turn to Antares and move your telescope 0.56° to the northwest. There you’ll find NGC 6144, a 9th-magnitude globular cluster 9.3' in diameter. In the open sky this would be a most easy object, but Antares must be out of the field of view if any success is to be expected.

Antares deserves a careful glance as well. It has a 6.5-magnitude companion ubout 3" to the west. First noticed in 1819 during an occultation of Antares by fhe Moon, the companion is said to glow green, but that is an illusion. The companion is easy in a 6-inch telescope, but you'll need a steady atmosphere. If ^re having problems with glare from the primary, try using a Lumicon deep-y filter. Although I haven’t tried it myself, I hear it does the job nicely.

Seemingly swimming against a current in the Milky Way, the 5.1-magnitude lobular M22 lies about 2° northeast of Lambda (A.) Sagittarii, the top of the

Teapot. Abraham I hie of Germany apparently discovered it in 1665 while f₍₎| 1

lowing the motion of Saturn. The problem in detecting this cluster is not with j_lsbrightness — which is nearly a full magnitude brighter than M13 — but with i_ls I proximity to the horizon and summer haze. It's nicely positioned, though, being I just east of 24 Sagittarii.

In 1992 Brian Skiff spied 6.4-magnitude M15 from the Texas Star Party. [f_snot terribly difficult to see with the unaided eye.The trick is to separate it f_ronia star of comparable magnitude immediately to its east. By the way. if you _0Wna large telescope, see if you can spot the dark patch with two dustlike lanes near the cluster’s center, which Webb first reported.

Two globulars are more demanding. Shining at magnitude 6.3, M3 lies in _avery star-sparse region of sky. Furthermore, it nearly abuts a 5th-magnitude star, so you'll have to resolve the two to make a positive sighting. Overshadowed by its stunning neighbor M13, the 6.5-magnitude globular M92 in Hercules is right at our magnitude limit. It is not only challengingly faint but also isolated northeast of the Keystone.

Finally there is M2, which culminates late on July nights. At magnitude 6.5 it. too, is at our preselected limit. But I’ve had no problem sighting it. I have seen it repeatedly from the bayous of Louisiana during my stint as a celestial navigator for the Air Corps.

5^s* = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dork Nebulo; GC = Globular Cluster; Gx = Goloxy; Open Cluster; PN = Plonefory Nebula; ♦=Star; ** = Double/Multiple Star; Var = Variable Star

Scanning the August Pole

What is the most neglected area of the entire northern sky? The north polar region, of course — especially for anyone who owns a German equatorial mount. It's a shame because, as Scotty reminded us, one advantage of living in the north temperate zone is that the polar region of the sky is available every clear night of the year. But Scotty had a way to solve this problem so that we could turn our sights to this rich but overlooked area. "Observers using equatorially mounted telescopes may find it difficult to sweep the sky so close to the pole," he wrote. "In this case, try turning the mount about 90° so the polar axis points east or west. Dobsonian and other altazimuth telescopes have no problem working this part of the heavens; lheir Achilles' heel is the area near the zenith." That done, observers should have no problems scanning the heavens around Polaris with the ease of an altazimuth mount. Such simplicity of thought was a well-known Scotty trademark.

The regions near the north celestial pole are usually neglected by amateurs, who seem more attracted to the spectacular sights farther south. But sometimes we overlook the obvious. Polaris, for example, is a variable star. In fact, it is the brightest Cepheid in the sky. Sky Catalogue 2000.0 gives its range as 0.15 magnitude over a 4-day period, but studies done during the 1980s show that the range ^ls decreasing, leading some astronomers to speculate that the star may cease to ^Vary altogether. Currently Polaris varies by only a few hundredths of a magnitude ^and is thus well below the range detectable by the eye.

Polarissima is the name John Herschel gave to the “nebula” he found closest to I e north celestial pole during his great sky surveys of the early 19th century ■Rare 8.1). More commonly called NGC 3172, it is a small spiral galaxy about 1' ^acr°ss and magnitude 13.5. Although some have seen it with telescopes as small ^s6 inches, under average sky conditions NGC 3172 will be a challenge for an 8-^nch- Here is an object that is better seen with high magnification. Try also for a ne P³*^r 8^a'^ax*^es J^{ust a} f^ew degrees from Polaris, in the far northeastern cor-^^r°f Cepheus. NGC 2276 and 2300 are only 6' apart. Both are 11th magnitude,

¹ NGC 2300 will be spotted first. It is round and 1' across, while its neighbor to

NGC 3172 is often called Polarissima because of its proximity to Polaris, the bright star at left.

the west is twice as big and does not stand out as well in the telescopic field.This pair stays at nearly the same altitude all year, providing a convenient test for sky transparency.

While near the pole, try for another tiny galaxy. NGC 6217 in Ursa Minor is 11th magnitude, and I estimate it to be about 1' long. (Catalog entries, often based on photographic images, list it as somewhat larger.) This spiral should be within the reach of any telescope 8 inches or larger, but on good nights I have found it with a 4-inch.This open-armed barred spiral is visible from north-temperate latitudes throughout the year and provides a good test for sky transparency.

Near the extreme western edge of Cepheus is the open cluster NGC 6939. Through a small telescope it appears about 5' in diameter and shines with a total light equivalent to a lOth-magnitude star. In their book Revue des constellations, R. Sagot and J.Texcreau describe NGC 6939 as: “Not very notable in a 3-inch 18-power refractor; a round milky spot with very faint stars in a 3%-inch at 45x. I*¹the catalogs, this open cluster is listed as being fainter than NGC 188, but it is f^areasier to pick up because the stars are concentrated in a smaller area of sky-From Springfield, Vermont, my 5-inch Apogee telescope held it in view even when stopped down to 2% inches. A 10-inch shows a sprinkling of stars. And only about 1° to the southeast, just over the border into Cygnus, is the fine galaxy

While scanning Cepheus, look for the star cluster NGC 7380. (North is to the upper right.)

NGC 6946. This spiral is easily seen in even small telescopes. It shines at 9th magnitude and is roughly 10' across.

Tucked in the southeastern corner of Cepheus is the bright cluster NGC 7380. Its 50 stars (Figure 8.2) are scattered over an area about 10' in diameter. Having a total visual magnitude of 6.4, NGC 7380 can be readily seen in binoculars. Small telescopes will reveal a conspicuous double star, magnitudes 7.6 and 8.6, at the southwestern edge.

The most northern galactic cluster in the sky, NGC 188, is also one of the oldest known, 14 to 16 billion years*. It is located just 4° south of Polaris and 1° south of - Ursae Minoris — a bright star that was engulfed by Cepheus when the constellation boundaries were redefined by Eugene Dclporte in 1930. NGC 188 is 15 across, so use low power. It contains some 150 stars, most of which are fainter than ^13,11 magnitude. Despite a total magnitude of 9, it is virtually invisible with poor ^lransparency, or in too feeble a telescope. On fine nights I see it as a ghostly glow

Gweni/y the age of the universe is estimated at 12-14 billion years, while the ages of some of the oldest 4rs in globular clusters are estimated to be around 13—15 billion years. As astronomers work on a more ^Ccu'ate determination of the ages of stars and the universe, this seeming paradox of stars older than the ^nive^ is being resolved. in thc 4-inch Clark refractor. In his Celestial Handbook, Robert Burnham j describes the appearance of NGC 188 in a low-power 6- or 8-inch telescope— ’ large but dimly luminous spot with only a few of the brighter members show’ individually." Although it shows nicely in an 8-inch telescope, you will have"¹⁸search it out from a few bright stars nearby that some people mistake f_Or tk° cluster. Back in Kansas, on a night when the naked eye reached magnitude 7 5 ⁶counted several dozen stars in NGC 188 with my 10-inch reflector at 86x

Inside the Cepheus pentagon is a more challenging open cluster, NGC 714-) John Herschel described it accurately as “a large, rich, loose cluster of stars _Of magnitude 10 or 11.” To me it seemed an evenly spread layer of small stars. Lo₀). for some faint stars in a patch 10' across. Finding them can be a problem, for the brightest single member (except for two obviously foreground stars) has been measured as visual magnitude 12.4. Hence, NGC 7142 does not show in a 2-inch finder, and I generally search with the main telescope after plotting the cluster on a detailed chart. High magnification helps after this cluster has been found One fine night in Connecticut, the 4-inch Clark at 40x showed an even glow in which a dozen stars twinkled. Since lOOx revealed more, 1 put on a Barlow lens to double the power again, and saw a host of minute stars.

Open cluster NGC 7510 in Cepheus is about 9th magnitude and 3' across. Of it, Canadian amateur Dunstan Pasterfield writes, “Very easy to find, an attractive object framed by surrounding stars. It has an unusual shape, like a very thin arrowhead that is slightly bent at the tip. A hint of nebulosity. About 7-10 stars — delightful thing.” Have others seen any nebulosity here? Could the impression of a glow come from faint stars in the cluster not seen directly?

More Sights in Cepheus

Though the north celestial pole lies in the constellation Ursa Minor, Cepheus reaches up to declination 88'/2°. Most of its bright stars are 20° or 30° from the pole, in the Milky Way where it crosses the southern part of the constellation. "Here one might expect many clusters and planetary nebulae," Scotty wrote, "especially since neighboring Cassiopeia has a profusion of them." But Cepheus is relatively poor in traditional deep-sky wonders. It has no dramatically bright galaxies (only one is plotted on Sky Atlas 2000.0) or any globulars. And, surprisingly, rich open clusters are not as profuse as one would expect from a Milky Way region. In all, one could say that Cepheus has few good objects. But "good" is a relative description, as Scotty reveals here. Remember, even a faint object can be a good one if it presents a challenge.

Thanks to their never setting from mid-northern latitudes, some of favorite double stars within 15° or so of the pole can be inspected whenever the mood strikes, or shown to a friend who drops in. The circumpolar doubles range from difficult binaries to glorious objects at low power.

_aris itself is a wide optical pair, first seen as double by William Herschel in Its two stars, magnitudes 2.1 and 8.9, are 18" apart. Argument still goes on ^ut the smallest aperture needed to show the companion. Long ago, William mwes suggested it as a test for a 2-inch, but it has been seen in smaller telescopes. Miy not make some systematic tests with a graduated set of cardboard jiaphragms on your own telescope?

An easy pair that can be split even in big tripod-mounted binoculars is Struve ₎₆94 (also written as X 1694) in Camelopardalis. It consists of a 5.3-magnitude star _ind a 5.8-magnitude companion, separated by about 22" and moving in parallel paths in space. The “I” prefix (often seen in star catalogs) means that a double star j_S listed in Wilhelm Struve’s famous catalog.

Look in Cepheus for Struve 2923, an unequal 9" pair. Its components, of magnitudes 6.3 and 9.4, should be resolved by 2- or 3-inch telescopes. This, too, is a common proper motion pair. Half a degree away is a difficult binary that makes an interesting object for larger amateur instruments: Struve 2924. This system of 6.6 and 7.0 magnitude stars has an orbital period of 226 years, according to the calculations of Wulff D. Heintz. The true orbit is actually nearly circular, but the apparent orbit is a highly foreshortened ellipse. Struve discovered this pair about 1830. when the separation was 0.8". In the 1930s it had closed to less than 0.2", and I've seen it widened to 0.5".

NGC 7023 is an object that Sky Catalogue 2000.0 calls “one of the bright reflection nebulae,” an encouraging description to say the least. It is centered^ a 6th-magnitude star that is easily seen in binoculars (Figure 8.3). From my _e°ⁿliest days as an observer I have notes that refer to the nebula as “real bright '■ and question why it is not plotted in Norton's Star Atlas. I suspect it is an e object for big binoculars.

Two rather difficult nebulae, on the other hand, are NGC 40 and IC 1470. NGC 40 is a lOth-magnitude planetary about 0.6' in diameter (Figure 8.4). Though located in a region devoid of bright guide stars, it was spied with my 5-inch Apogee telescope. IC 1470 lies on the galactic equator near the Cassiopeia border. On a good night it should be an easy object for an 8-inch telescope. Tom Reiland. of Glcnshaw, Pennsylvania, was observing IC 1470 with an 8-inch f/5.3 Newtonian when he happened upon a smaller and fainter object about 12' south and slightly west of it. At first he thought it might be a comet, but increasing the power from 54x to 130x revealed half a dozen stars spread across 30" with a hint of nebulosity. IC 1470 is now regarded as a diffuse nebula, though at one time it was thought to be a planetary. Using a pair of 5-inch binoculars, I searched quite a while before locating this faint object, which is only 1' across. But once found-it was relatively easy.

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_r|,_ara. California. A recent letter tells of his surprise when his observations of ■ gaseous nebula in Cepheus showed more detail than the famous Sir John jjerschel saw. This object is NGC 7129. Herschel described it as “a very coarse . |_{e s}t_ar involved in a nebulous atmosphere; a curious object. The nebula is xtremely faint and graduates away.” Tire stellar triangle is about 2' in extent. Thomson, however, has seen five stars. He writes: “At 70x, three stars are visible ■ the nebulosity. A in the south following part. B in the south preceding. The bird fainter star, C, is northeast of A. With 160x, a fourth star was visible slight-I southwest of C. Using 222x, I could glimpse a fifth star just southeast of A. All five components were readily visible with 333x.”

The 18%-inch speculum-metal mirror used by John Herschel for his observations in 1829 was perhaps equivalent to a modern 12-inch aluminized mirror. One indication of Thomson’s observing skill is his independent rediscovery of the very faint galaxy NGC 5296 in Canes Venatici, which was missed by both William and John Herschel and was first noted by Lord Rosse with his 72-inch

1 looked at NGC 7129 with my 4-inch Clark refractor on a night so clear that the Triangulum Galaxy M33 was intermittently visible to the naked eye. At 120x, the nebula and John Herschel’s three stars were clearly seen, but even with 310x there was no trace of the other two stars.

The Great Planetaries of Summer

"They are ephemeral spheres that shine in pale hues of blue and green and float amid the golden star currents of our galaxy." What Scotty was describing, of course, are the planetary nebulae, which, he extolled, "are often the delight but also the bane of amateur astronomers." Bright planetary nebulae are uncommon, and planetaries of all shapes are rare because their lifetimes are short. The Messier catalog contains only four of them — M27, M57, M76, and M97. To date, only about a thousand are known, and perhaps only a hundred of them are suitable for amateur telescopes. The most famous planetary in the heavens is unquestionably M57, the Ring Nebula in Lyra.

To some people, the ethereal gas bubbles of planetaries have a compelling pull all their own. They float on the foam of the Milky Way like the balloons of our childhood dreams, so delicate they appear. If you want to stop the ^w°rld and get off, the lovely planetaries sail by to welcome you home.The Ring ^Nebula, M57 in Lyra, is one of the best-known objects in the summer sky figure 8.5). It was discovered by the French astronomer Antoine Darquier in

⁹ while comet hunting with a 3-inch refractor. He described it as “a very ^u nebula, but perfectly outlined; as large as Jupiter and looks like a fading Planet.”

Figure 8.5 MS 7 in Lyra appears ringlike because we are looking down a barrel of gas cast off by a dying star thousands of years ago.

By Herschel’s time its “smoke-ring” form was known and justly admired. William Herschel thought it to be a ring of stars just beyond the resolution of his telescopes. His son John first called attention to the fainter nebulosity which fills the interior of the ring, likening it to gauze stretched over a hoop. In Ireland, Lord Rosse used his 6-foot speculum-metal reflector in the 1840s to detect structure in M57’s ring, but curiously he does not mention the central star first seen with a smaller telescope by the German Friedrich von Hahn around the year 1800. (Rosse does say that he never really viewed M57 under excellent conditions when his 6-foot reflector was working at its best.) All this reminds us of the superior optics which today’s amateurs enjoy, for under good conditions the central nebulosity and star can be glimpsed in apertures as small as 6 and 10 inches respectively.

The Ring Nebula differs from most planetaries by the almost perfect sharpness of its outlines, and the completeness of the ring form, in contrast to such objects as the Dumbbell Nebula, where visual scrutiny would never suggest the typical planetary construction. However, long-exposure photographs of M57 show a second ring outside the first, of a fragmentary and curdled appearance. Also designated NGC 6720, M57 is easily found halfway between Beta (0) ^anc* Gamma (y) Lyrae. It is oval, 80" by 60", and is of the 9th magnitude visually.

For early observers, the trick was to see it as a smoke ring with a dark core. As the average amateur’s telescope became larger and eyepieces better made, the ring was no longer a challenge, especially since this object bears magnification well. Appearing a bit more than 1' across, M57 looks like a 9th-magnitude star m finders.The Apogee telescope shows the ring as very bright, but no other detail • visible. At powers of 250x and up. a curious effect takes place. The oval outline of M57 takes ^{on a} *^emon shape with the ends of the oval appearing rather pointed They also appear more diffuse and wispy. A power of 600x, however, is none ₀ great if there is sufficient aperture to support it. Even at high magnification, _thc interior of the nebula retains a thin film of haze that can show some structure.

I have probably looked at the Ring Nebula with a greater variety of telescopes than I ha^{ve at an}Y other heavenly subject. One of my best views came with the 12-inch f/17 Porter turret telescope on Breezy Hill in Springfield, Vermont, the ite of the annual Stellafane convention. At 200x the ring was bright, slightly _elon°ated, and of uniform luminosity. An increase to 600x changed the picture dramatically. No longer was the smoke ring evenly bright. Instead, two sides of the ring were made up of curved and twisted streamers. The oval now had pointed ends, and the central region was full of turbulent detail.

The sky above Breezy Hill that night was superb, with the naked-eye magnitude limit approaching 7. M33 could even be glimpsed without optical aid (a favorite test of mine for those rare nights of really excellent observing conditions).

So what does it hold for the explorers of the wilds? In 1874, Edward S. Holden studied it with the 26-inch refractor at the U. S. Naval Observatory in Washington, D. C. He commented that the interior of the ring appeared to be filled with “glistening points” of light. TTiis report remained unique for about a century. In 1979,1 was looking at the Ring with the Porter turret telescope using 600x.To my surprise I, too, saw a scattering of faint stars across the center of the nebula and against the brighter parts of the ring. However, these stars were not visible in the 20-inch Clark refractor at Connecticut’s Wesleyan University. But that telescope is plagued by light pollution. The problem today is to see the gossamer bands of nebulosity that cross the planetary’s core. They are visible in the Porter telescope. This instrument is particularly noteworthy for its high-contrast views of the planets and deep-sky objects.

On a top-class night, a 12- or even 10-inch telescope can show the planetary’s central star. In moments of exceptional atmospheric conditions a 12-inch or larger instrument may reveal a scattering of stars across the central vacancy and even amid the ring itself. However, stars do not spread beyond the outer edge. 1 ve checked several photographic atlases and noticed a definite lack of faint stars around M57. From my own dark-site observations I know that the edge of the Milky Way does cross this region. Could there be a dark halo surrounding the glowing ring that blocks the view beyond? If so, why do we see stars inside the ring?

For those of you interested in viewing the central star of M57, it is worth not-^ln8 that over the years, estimates of its magnitude have ranged from 14.5 to less than 16. Although some have suspected the star as being variable, the data arc far hom conclusive, as anyone who has tried to estimate the magnitude of a star embedded in nebulosity knows. Needless to say, the central star is very difficult to ®bnipse. It should be a routine object for a 12-inch telescope, but often cannot be ^Seen with a 17'Z-inch. 'fire usual technique of increasing magnification to darken thc sky behind a faint star docs not work as well as expected. This is due to th_efaint nebulosity filling the interior of the ring and reducing the star’s contrast with its background. A telescope's focal ratio may play some part in rendering the st_arvisible. At f/17 the 12-inch Porter turret telescope usually makes easy Work of M57’s central star, while significantly larger apertures have difficulty.

Try also looking for three galaxies that are near M57; one is even in the same field of view. The brightest of the three, NGC 6713, lies just a bit more than 1» northwest of the Ring. Albert Marth discovered it with the 48-inch speculum metal reflector that William Lassell constructed in the early 1860s on the Mediterranean island of Malta. I wouldn’t be surprised if a modern 16-inch reflector, with its high-efficiency optical coatings, had a total light-gathering power similar to that of the speculum-metal mirrors in Lassell’s telescope. The NGC 2000.0 catalog lists NGC 6713 as photographic magnitude 14, so visually it might appear a little brighter — say 13.2. Another galaxy is NGC 6700. located about I/2⁰ southwest of M57. Edouard Stephan discovered this one with the 31-inch silver-on-glass reflector at Marseilles Observatory in France. NGC 2000.0 lists it as photographic magnitude 14 as well, so it should appear similarly brighter visually.

Much more challenging is a tiny 15th-magnitude barred spiral discovered by E. E. Barnard. IC 1296 lies just 5^Z northwest of the ring. I do not know of any amateur sightings of this galaxy.

The Dumbbell's Many Faces

Next to M57, the Dumbbell Nebula (M27) is the sky's second most sought-after planetary nebula. Its ghostly green orb is really the glow of dimly lit shells of gas blown off an aging star shining weakly at the nebula's core. As the shells expand, they fade, and only a few tens of thousands of years pass before their ghostly shapes disperse into space. The extreme limit of visibility of the expanding shell and of its tiny illuminating source, a white dwarf star, intrigued Scotty. Naturally, he loved to share the visual mysteries of planetaries with his readers. And he couldn't resist tossing out a planetary nebula challenge or two to those who would pursue them. The Dumbbell was not lacking in challenges for Scotty or his readers.

The August sky contains many delightful planetary nebulae — ephemeral spheres of blue and green gas that float amid the pearly star currents of the Milky Way. Certainly one of the most observed is the Dumbbell Nebula, M27, m Vulpecula (Figure 8.6). Binoculars will show it, but no instrument ever exhausts the additional detail that may be seen as larger telescopes are turned to it.Thirty years ago my mail was filled with complaints from amateurs who had difficulty finding M27, but I haven't heard such remarks for the past 10 years. This is a tribute to thc growing observing skills among the fraternity of today’s amateurs. H

. iu’re having trouble locating it, here's one method that works well for me. Set ' _ur finder on Gamma (y) Sagittae, the head of the celestial arrow. Sweep about 50 north and you should see an M-shaped pattern of stars composed of 12,13,14, 16 and 17 Vulpeculae; this group is more conspicuous to the eye than most star chaft^s V°^{u to} b^e'*^eve- ^27 is just !4° south of the M’s central star.

The noted English observer Thomas W. Webb saw M27 as “two hazy patches in contact.” and it is this appearance that gives rise to the nebula's popular name. However. I don't believe that many observers see the dumbbell shape without having a bad wrench to the imagination. John Mallas. who observed with a 4-inch refractor, drew M27 as a rectangle twice as long as it is wide. With my 4-inch Clark refractor, a quick look reveals the planetary as two cones with their apexes in contact. After finding the best eyepiece for the evening's _sky conditions, and by using averted vision, 1 usually see the faint nebulosity between the brighter parts of thc cones. By gently rocking the telescope back and forth — which sets the W planetary in motion and helps the eye capture the faintest extensions of light — I found the end result is a full circle of light, just as

one would expect of a planetary. The luminosity of the interior varies greatly, but the circular outline remains firmly fixed.

It is hard to assign a “best” type of telescope for viewing M27. My 5-inch Apogee telescope with a fixed power of 20x shows it as a bright sphere with the dumbbell shape rather mild. My 10-inch, f/8.6 reflector shows M27 much better at 300x by means of a Barlow lens than at the same power with a short-focus eyepiece. The latter left the sky gray, and contrast with the nebula was poor. The Sorter turret telescope reveals intricate inner detail and a strong edge all the way ^around the nebula. M27 is often cataloged as having dimensions of 8' x 4', but as Mentioned above, it really appears round and about 8' across, especially on phonographs. Its total brightness is equal to that of a 7.6-magnitude star, and there is a l^h-magnitude central star that is a difficult object for most amateur telescopes.

The fact is, this fickle planetary has as many shapes as there are observers its appearance can even vary from minute to minute as observing conditio ’ change. Several years ago I had a good lesson in just how critical a role the atmosphere plays in observing faint, nebulous objects. During May 1983. ] \_v._rin western Pennsylvania when Comet lRAS-Araki-Alcock raced across the sk from Draco to Cancer. It moved so swiftly that within minutes 1 could detect change in its position with the naked eye. What really interested me, however was the coma’s diameter. At times it was 2° or 3° across, while at other times it was fully 6°. This must have been due to atmospheric changes that otherwise would have gone unnoticed.

According to Burnham’s Celestial Handbook, M27 appears to be expanding at the rate of 1" per century. If this rate has remained constant, then the nebula is perhaps 48,000 years old — if it has slowed over the years then the object could be much younger.

So the test with M27 is not in seeing it — the glowing bubble, as I mentioned, should be easy in finders if the sky is dark — but rather in what is seen. Can vou trace the faint wisps of nebulosity from the ends of the bar to where they meet above and below it?

Houston's Uncertainty Principle

The next time you're out under a very dark sky, look up at the Milky Way. How wide is it? The answer is not as simple as it seems. The answer depends not only on where you look but how you look. It also depends on the conditions and state of the atmosphere and on your own physical condition and eyesight — all factors that vary with time. Thus, the "shores" of this Galactic River can be as hard to define as the extended coma of a comet. Even star charts do a poor job of tracing the visual breadth of this, the sky's largest deep-sky wonder. But the problem doesn't end there. The same difficulty we experience in this simple exercise with the naked eye applies also to the telescopic observing of nebulae, especially of the planetaries, whose expanding shells gradually fade until they blend with the sky background. Scotty was excited about this visual conundrum, which he explains here.

This may sound foolish, but all my life I’ve wanted to find the edges of the Milky Way. Obviously our galaxy can’t go on forever. It must stop at some point. But where? On any clear night I can clean my glasses and wander out to a dark corner of my yard with a ruby-colored flashlight and star charts in hand. After letting my eyes dark-adapt, I can carefully plot the apparent edges of the Milky Way (Figure 8.7). The rub is, however, if I repeat the process two hours later, I usually get a border that is nowhere near my original one.

Books and atlases don’t seem to offer much help. Norton's Star Atlas plots the boundaries of the Milky Way in great detail, but they’re not what I see. The atlas’s preface concedes that the boundaries arc difficult to define, and that the outline on the charts is based on observations by the 19th-century astronomy popularizer Richard A. Proctor. Thus, my 1957 edition of Norton’s uses data about a century old!

WilTirion's Sky Atlas 2000.0 might seem like a better bet since it was first published in 1981. The Tirion charts show more twists and turns at the edge of the Milky Way. but here again they are often quite different from what 1 see. The introduction to this atlas notes that the outline shown is one that the Dutch astronomer Antonie Pannekoek prepared in the 1920s. I’m not sure how he derived it. but it is probably a combination of photographic and visual observations. both of which have their limitations.

Over the years my conviction has been growing that the atmosphere is really what determines the limits visible to the eye, and the atmosphere can change on a time scale of minutes. In late 1985 I set out to watch Halley’s Comet with my 5-inch 20x Apogee telescope when it was near the Pleiades. At 11:30 p.m. sweeping did not turn up the comet; I had to revert to charts to find it. The cosmic

Figure 8.7 The Milky Way is an awe-inspiring sight on a cloudless dark night. Here, Deneb (upper left), Vega (right) and Altair (lower left) seem to frame the galaxy's star clouds.

visitor looked like a 7th-magnitude star with barely a trace of a blur at its edg_CsAt midnight I looked again and found a whole different object before me. Th comet was easily swept up and the bright coma appeared about 1° across R 12:20 a.m Halley had returned to being a slightly nebulous star.

All this is worth remembering by the deep-sky hunter in search of faint gal_axies, supernova remnants, stray H II regions, and diffuse planetary nebulae. Yo_ucan use every trick in the book to press your telescope to its limit, but the atmos phere is still going to be a highly variable "filter." 1 call it Houston’s Uncertainty Principle, and it confounds your ability to predict the magnitude limit of a gj_Ventelescope to no better than one full magnitude.

In my flirtations with the boundary of the Milky Way, I have spent a lot of tintc looking at the region around Lyra. The Tirion charts show the Milky Way's edge crossing the lower section of the lyre, including the whole area between Beta (p) and Gamma (y) Lyrae and its resident deep-sky showpiece M57,the Ring Nebula.

Edouard Stephan also discovered several star clusters here, including one involving the bright, naked-eye double star Delta (8) Lyrae. This group is bright but sparse, having only a dozen or so stars in a 2O'-wide area. It is easy to see in binoculars. The bright double may lead the eye astray and be the reason so few observers seem to be aware of the rest of this cluster.

From Delta Lyrae it’s only a short skip to the nearly equilateral triangle of stars Epsilon (e), Zeta (Q, and brilliant Alpha (a), or Vega. Few amateurs seem to know that all three, and not just Epsilon, are double stars. Epsilon (e) of course, is the famous Double Double, whose bright components are separated by 3Z' and create a test for naked-eye acuity, much more so than Alcor and Mizar in the handle of the Big Dipper. As a youth I could split them easily, but I have not been able to do this for several years. Each component is itself a pair — the separations are currently 2.6" and 2.3" — well within the range of a 3-inch telescope.

I’ve never met an amateur who claims to have resolved Vega. Perhaps most are not aware that it has a companion. Brilliant Sirius and Antares are well known as binaries, but unlike them Vega is just an optical pair with no physical connection between the components. At present the 9.5-magnitude companion lies about 1' south of the magnitude 0 primary. The glare will make this a difficult pair at best. Don’t be confused by another 9.5-magnitude star 2' northeast of Vega.

The third member of the triangle, Zeta, is an easy pair. The 4.3-magnitude primary has a 5.9-magnitude companion YZ to the southeast. But a real challenge would be to look for a 15th-magnitude star cataloged as being just 25" northeast of the primary. It would be interesting to know the accounts of your adventures in looking at these stars.

Telescopic Delights in Delphinus

The tiny diamond-shaped form of Delphinus is popular among summer stargazers. (My wife, Donna O'Meara, loves to spot it whenever she's looking up on a warm

r summer's eve.) Like the Pleiades, this small but tight grouping of moderately bright suns has the power to draw attention to itself. "Unlike many of the large _consfell^at’^{ons t}*^iat date ^,o antiquity," Scotty wrote, "most smaller asterisms are the l_lindiwork of celestial cartographers from the 17th and 18th centuries. There are xceptions, however, and one of my favorites is Delphinus, the Dolphin." Scotty explained that his love for Delphinus was a long-lived one. "I became well acquainted with Delphinus when I joined the American Association of Variable Star Observers in the 1930s and started doing 'serious' astronomy," he wrote. Indeed, the first variable star he would log in his record book would be Z Delphini. The constellation's 189 square degrees also offers a fine blend of stellar and deep-sky wonders, making this delightful constellation a naked-eye, binocular, and telescopic attraction.

Summer lies hot and tranquil on the land. The gigantic storms of winter and the turbulent atmosphere that accompanies them are only memories now. At this time of year the seeing is steady all night.

West of the meridian in late evening lie the great star fields dancing with the brilliance of Sagittarius, Scorpius, and Scutum. The eastern sky, however, is a virtual desert of bright stars. The Great Square of Pegasus has little to offer the naked-eye observer, and Equuleus is likewise dim. On nights when a bright Moon floods the heavens with its golden light, the eastern sky appears almost devoid of stars. Near the meridian, however, is the small constellation Delphinus the Dolphin (Figure 8.8). To the eye it appears as little more than an overgrown asterism, but it contains some compelling objects for anyone with a telescope.

Delphinus has a distinctive diamond of stars forming the creature’s head. While these have never received official cluster status, there is some question as

The constellation Delphinus looks like a diamond with a tail and can be found about 12° northeast of brilliant Altair, the brightest star in Aquila, the Eagle.

to whether several of them are physically related to one other or to fainter star.-in the immediate area.The constellation is thinly covered with the outliers of th Milky Way and galactic dust as well.This blocks our view of the universe beyond so the area lacks the profusion of galaxies that are visible farther to the east

Nevertheless. I developed a fondness for Delphinus years ago when I beg_anmaking observations for the American Association of Variable Star Observer The area was rich in variables, and I could make half a dozen estimates in l_esstime than it took to search out a single star in a less crowded field.

In my youth I knew Delphinus as Job’s Coffin, a moniker whose origin even such star-name experts as Richard H. Allen acknowledged as being lost in the sands of time. Although my library is limited, the term appears in a copy _Of Elijah H. Burritt’s Geography of the Heavens, published in the 1830s. I suspect that the name was just one of those fashionable tags that caught on among skywatchers. Today we’re surrounded with similar fads drawn from popular music television commercials, and adolescent attire. (Can anyone pinpoint the source of ripped jeans being a fashion statement?)

On a similar note, at one Stellafane convention in Vermont I heard a 20-year-old amateur refer to the star Betelgeuse as “beetle-juice." While many readers are familiar with this term, I never encountered the pronunciation before World War II. In fact, I wonder if it originated with an Army Air Corps cadet at a military base where I taught celestial navigation during the war. One of the cadets was having trouble saying Betelgeuse, so he changed it. Before long even the experienced navigators had picked up the altered pronunciation.

Delphinus has several noteworthy double stars. Gamma (y), at the northeast corner of the diamond, is a beautiful pair with a 4.5-magnitude primary and a 5.5-magnitude companion some 12" to its west. Although the pair is physically connected, the orbital period is so slow that the position angle of the two stars has barely changed since it was first measured by Wilhelm Struve in 1830. The pair has long been known for its contrasting colors, but there is some question as to exactly what the colors are — different observers report different combinations. All agree, however, that Gamma Delphini is a splendid sight in small telescopes.

In the 1930s I was at the University of Wisconsin and had access to Washburn Observatory’s 6-inch Clark refractor, used by Sherburne W. Burnham to observe double stars. One of the many doubles he discovered with that telescope was Beta (P) Delphini, at the southwest corner of the diamond. The components have magnitudes of 4.0 and 4.9, and, though an extremely challenging object for amateur telescopes (the pair’s separation varies between 0.2" and 0.65"). Beta Delphini has an orbital period of only 26.6 y cars. For about half of the orbital period of the pair, the stars are separated by about 0.30". By the turn of the century the stars will be nearing maximum separation, the most likely reason Burnham succeeded where other great double-star observers had failed is that he chanced upon the pair when it was near its maX' imum separation in August 1873.

In 1950 I examined the star with my newly completed 10-inch reflector. Then separation was near a maximum of 0.6" with the companion due north of the ’marV- My first attempts to split the pair failed because the companion was lost ■ the diffraction spike caused by the telescope's secondary mirror holder. Success came only after rotating the tube 45° in its cradle to shift the position of ₍he spike. Ten years later the companion had moved roughly due east of the primary ^a°d ^t'^ie separation had shrunk to a minimum of 0.2". I was unable to detect _even a slight elongation of the double star’s image. Try experimenting with masks to determine the smallest aperture which will show the pair.

Alpha (a) Delphini is a challenging double for a different reason. With a sep-aration of almost 30" (two-thirds the apparent diameter of Jupiter), the pair would seem to be within reach of the smallest telescope. But at magnitude 13.3, the secondary is 9'/? magnitudes (more than 6,000 times) fainter than the primary. It's located to the southwest. An old trick is to place a bright star just outside the field of an eyepiece when searching for faint companions.

Distant, shimmering NGC 7006 is one of the most remote globular clusters that appear to swarm around the Milky Way Galaxy.

The interesting globular cluster NGC 7006 lies about 3!6° due east of Gamma (?) Delphini. If you have a motorized drive, switch it off, set your telescope on Gamma. and 15 minutes later the globular will be in view (Figure 8.9). Though readily detectable in a 3-inch instrument, it is small — 1.1'in diameter — and so concentrated that it may at first be mistaken for a lOth-magnitudc star. Although a relatively easy object for a 6-inch telescope, this cluster is among the most distant globulars known, located more than 110,000 light-years from Earth. l__artelescopes may show it with a clumpy appearance, but I doubt it _canresolved in any amateur instrument. NGC 7006 affords an interesting contr^ with the nearby great globular cluster Ml5, in Pegasus, which can be seen with thc naked eye.

Somewhat easier is the globular NGC 6934. More than 5' in diameter and shining with the total light of a 9th-magnitudc star, thc cluster can be glimpse in binoculars. Because of its setting, I find it a particularly pretty object for rich field telescopes. (Figure 8.10)

Another globular cluster easily seen in small telescopes or binoculars is NGC 6934. Through larger telescopes, individual stars can be seen around the edges and near the concentrated knot of stars at the center.

NGC 6905 is a planetary nebula situated in a coarse clustering of stars in the very northwest corner of Delphinus. William Herschel discovered it in 1782. and his son John Herschel speculated on a possible connection between the nebula and the many faint stars around it. Its 12th magnitude elliptical disk is about 45 in diameter (roughly the same size as Jupiter’s disk) and is relatively easy for a 6-inch telescope under good skies. On one of those exceptionally rare nights when the Connecticut atmosphere forgot that its main function is to depress amateur astronomers, I fished out NGC 6905 with my 4-inch Clark refractor. At least a 10-inch telescope is needed to make out the 14th-magnitude central star. Barbara Wilson of Houston. Texas, reports seeing a lot of internal structure i" NGC 6905 with a 20-inch reflector. The central star has an extremely high sur face temperature of about 100,000° Kelvin.

fxlGC- 6891 is a small object about 12" in diameter, roughly three times small-,_r than NGC 6905. At low magnifications it looks almost stellar. The planetary .. |i_Sted in Sky Catalogue 2000.0 as being of photographic magnitude 11.7. but it seems brighter visually (other sources list it as between 9th and 10th magnitude). I have seen it front Connecticut with a 4-inch off-axis reflector. Observing with _a 16-inch reflector from the Sonoran desert outside Tucson, Arizona, Ron Morales notes that NGC 6891 resembles an unresolved globular star cluster.

Unlike many authors,T. W. Webb took great pleasure in writing about rich star fields. These are not the discrete objects like star clusters and galaxies that interest most deep-sky observers, but rather wonderful starry vistas that are nothing more than chance alignments of random suns. Webb wrote about them simply because they were delightful to look at.

Philip Harrington has a similar attitude in his book Touring the Universe Through Binoculars. Accordingly, he lists several asterisms that are new to amateur observing guides. One such group involves 6th-magnitude Theta (0) Delphini. Harrington notes that there are about two dozen stars here of 9th magnitude and brighter that are visible in binoculars.

About 1 '/° southeast of Theta lies NGC 6956, a small galaxy discovered by William Herschel. It is about 2' across and, by my estimate, magnitude 13.2. While Herschel considered it “very faint” as seen with his 18Z-inch reflector, perhaps the telescope’s speculum-metal mirror was tarnished or thc sky conditions were unfavorable on that particular night. Today NGC 6956 can be held easily in a 4-inch refractor.

Although galaxies are sparse in Delphinus, NGC 6928 is the brightest member of a foursome located I¹/’ south of Epsilon (e) Delphini. Its cigar-shaped disk is about 2' long and magnitude 12'/’. An 8-inch telescope should easily snare it on a good night, but a larger aperture will probably be needed to see its companions. They all lie within 14° of NGC 6928.

Ast = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dork Nebula; GC = Globular Cluster; Gx = Galaxy; OC = Open Cluster; PN = Planetary Nebula; ♦ = Star; »♦ = Double/Multiple Star; Vor = Vorioble Star

VVandering Through Lacerta, the Lizard

No region in the heavens is barren," Scotty wrote. "No constellation is fruitless tor the observer. Even a lifetime of exploring the celestial display cannot exhaust the surprises that dance so beautifully before the amateur astronomer." His words _ring true because some regions of sky remain frequently overlooked by backyard observers. Consider Lacerta, the Lizard. In the September 1972 Deep-Sky Wonders, Scotty told how James P. Brown of Kingsport, Tennessee, pointed out to him that, for many years, the column had curiously omitted that constellation. Tucked between Cygnus and Andromeda, Lacerta extends almost a full hour in right ascension and about 20° in declination, but its brightest star shines at a dim 4th magnitude. "Inconspicuous as Lacerta, the Lizard, may be," Scotty proffered, "it nevertheless offers some good open clusters for September viewing." / \ September evenings, the small constellation Lacerta crawls high overhead. This celestial lizard was created in 1687 by Johann Hevelius to fill the void between Cygnus and Andromeda. Some eight years earlier, the French astronomer Augustin Royer used the handful of naked-eye stars in this area to portray a scepter and hand of justice commemorating King Louis XIV of France. And, almost a century after Hevelius’s figure, the German Johann Bode used ’hese same stars to form Frederici Honores as a tribute to his sovereign Frederick •be Great. But just as the rule of a monarch is temporary, so too was the accep-^lance of these asterisms, and today only the lowly lizard occupies this space.

Lacerta is a weak little constellation tucked alongside the galactic equator and ^niUcb overshadowed by its vivid neighbors Cygnus and Cassiopeia. Because ^acerta’s naked-eye stars are all inconspicuous, they provide an opportunity for observers to test their skills at finding their way far from bright guidepost stars. Its ghtest star, Alpha (a) Lacertae, is only magnitude 3.8, so from a light-polluted ^an location the celestial lizard may be a bit difficult to find. Because of a lack tel ®^u*d^{e stars t0} help point the way, this area is a good place for the novice ^Sc°pe user to practice hunting with a finder.

There is a good reason why amateurs should get familiar with Lacerta <jj 1910 three novae have blazed out in this area, and more will certainly _Co^nCcBecause there are no stars brighter than 4th magnitude to distract the obse ^C‘ a relatively faint interloper should be evident. ^Ver’

Though it has no spectacular deep-sky objects, it does contain several br „k clusters that can be reached with modest instruments. As many observers kn^ areas of the sky that appear empty to the naked eye often hold interesting _g0o*’ ies for a small telescope. Sentiment often drives me to take a look at two mult, pic stars in Lacerta that I learned of in my youth, while surveying the sky with copy of the venerable Norton’s Star Atlas. Struve 2894 consists of a pair of 6 1 and 8.3-magnitude stars separated by 16".This puts them well within the grasp _Of a 2-inch telescope. The second, 8 Lacertae, is a pair of 5.7- and 6.5-magnitude stars about 22" apart. Two other stars of 9th and 10th magnitude lie 82" and 49" from the primary, respectively, and may be part of the same physical system.

NGC 7243 is the only cluster in Lacerta mentioned in the classic observing guides by William H. Smyth and Thomas W. Webb (the 1881 revision of Smyth’s Cycle of Celestial Objects by George F. Chambers added another open cluster NGC 7209). Smyth notes that the surrounding area is very rich, especially to the north of the group. To find NGC 7243 look for a small keystone of stars, including Alpha, Beta (p), and 4 Lacertae, which should fit within the field of any finder. NGC 7243 is along the southwest edge of this keystone, about 2'Z° west and a

The open cluster NCC 7243 is a fine sight in large binoculars and small telescopes.

little south of Alpha. It is a splashy coarse star grouping about 20' across (Figt*^re9.1) with a total magnitude of about 7.5, making it a good object for deep-sky binoculars with 80-mm objectives. Sky Catalogue 2000.0, however, lists the group as having a total magnitude of 6.4, which might make it visible to the naked eye under the best observing conditions.

The cluster stands out especially well from the stellar background when I ^st°P my 4-inch Clark refractor down to 1.8 inches. According to Revue des constell°

■f

I _y by R- Sagot and Jean Texereau, NGC 7243 in a 4-inch at about 5()x is a rich _gU]ar cluster of many stars between 9th and 1 lth-magnitude. The number of "' "' increases from about 15 in a 2-inch to 60 in an 8-inch. I found no definite ^S' ^r • in a 12-inch recently, but counted at least 80 stars within a !4° area. Look for ide double star at the cluster’s center, particularly if you have a 6-inch or larger *' cope. Try using different magnifications on this cluster. Often certain features f object are apparent only at specific magnifications. This is also an interesting ⁰ . ₁₁₀ try sketching. First rack your eyepiece out of focus to the point where nlv the brightest stars are seen. Add these and continue the process until sharp focus reveals the faintest stars.

About 4° southwest of NGC 7243 is NGC 7209. Its rather scattered bright stars figure 9.2) cover an area roughly 20' in diameter and are visible in my 2-inch finder Try star-hopping from the first cluster to the second one by following the small ^^emicircle of naked-eye stars 4,5, and 2 Lacertae. NGC 7209 is slightly smaller and ^ainter than NGC 7243. It stands out nicely from thc Milky Way background of ^^ar dust, lying within a rough pentagon of five brighter stars that can all be seen

the field _of _vj_ew ;_s y₄° _or |_arg_er. As many of the cluster's stars are between 9th and 10th magnitude, NGC 7209 is excellent in my 4-inch refractor. It _S|_1Qmore than 50 stars in a 6-inch. Some amateurs call this object triangular but I wonder whether they have been looking at NGC 7243 instead. Read-who record their impressions of this cluster should note instrument size m nification. and sky condition. Look for an orange 6th-magnitude star 15' north east of NGC 7209.

^3St of 4th-magnitude Beta Lacertae. This lOth-magnitude cluster lies on a rich back ground, which might be a hindrance since NGC 7296 is only 4' in diameter At 20x my 4-inch Clark refractor had a difficult time with this object. Glare from 4th-magnitude Beta and the rich Milky Way background made the cluster hard to pick up. Yet NGC 7296 can be found with a little patience. By increasing the refractor’s magnification to 80x, NGC 7296 was easily found, and the view at 150x was even better. Sweeping for the cluster at these higher magnifications is made easier by bright Beta Lacertae — if you get lost, return to the star and begin the search again. After examining the cluster at 150x, try sweeping nearby, or just letting the stars drift. This is an excellent way to discover many curious sights never seen during low-power sweeps.

Near the northern border of Lacerta, just west of the halfway point on a line between Beta Lacertae and Epsilon (e) Cephei, is a rather difficult open cluster. NGC 7245. It is only 5' across and of magnitude 11.5. NGC 7245 can be identified in 20 x 65 binoculars but is much more satisfactory in a 10-inch telescope. Recently, I could not locate it with a 5-inch at 20x, but when I switched to my 4-inch refractor at lOOx it was clearly seen. There is a triangle of three stars between 8th and 10th magnitude here. More than a dozen stars can be seen with a 12-inch telescope, but perhaps only half this many are within the grasp of an 8-inch instrument.

Somewhat richer than NGC 7245 is the open cluster IC 1434. Generally, objects in the Index Catalogue supplement to the NGC are faint and hard to locate, but the cluster IC 1434 is easily found. Continuing on a straight line from 9 Lacertae to Beta Lacertae for about the same distance that separates these stars will put you in the cluster’s vicinity. IC 1434 is an 8' grouping of perhaps 30 stars. Of 10th magnitude, it is a dull little cluster, but one that is improved considerably by running up to 150x or 200x and using averted vision.

As viewed from Connecticut with a 6-inch. IC 1434 appears as a compact ball of faint stars, about 6' to 8' in diameter; I have the feeling that this object might be a very pretty sight in a 16-inch telescope.

The group lacks solidarity and appears as if several clusters have been jumble^ together.The English amateur Guy Hurst, writing in the Webb Society Deep-Sky Observer’s Handbook, Vol. 3, Open and Globular Clusters, mentions that the cluster seems backed by "considerable haze” (by the way, this handbook incorrectly states the cluster is in Cygnus). The surrounding sky is quite rich, and 1 recommend that you spend some time just sweeping the nearby area.

a cluster missing from most catalogs and charts is NGC 7394. Canadian rver Pat Brennan describes it as "a coarse grouping about 10' by 3' across _{h a} brisht star at the southeast end." In addition to the bright star at its south-'^V8 -nd there are about 10 fainter ones. Since the field is not particularly rich, the ^C -r can be easily recognized! When John Herschel swept up this grouping in ^C 79 he noted in his record book that the measured position referred to “a dou-. star the last of a poor cluster of about a dozen stars.”

^NJore challenging than any of these clusters is the 12th-magnitude planetary _ebula IC 5217. It is located just slightly northeast of center in the stellar keystone

The challenging 12th-magnitude planetary nebula IC 5217 in Lacerta is roughly 8,000 light-years distant.

Quintet (see Sky & Telescope for Marell 1977. page 170). The latter is a group ₀much fainter galaxies, very difficult for amateurs, lying 30' to the south-southw °

Cruising Through Cygnus

"If one constellation dominates September evening skies," Scotty said, "it is the one known to the ancients as Cygnus, the Swan, and to less imaginative moderns as the Northern Cross." Regardless of how we see the constellation, one thing j_s f_Orsure: few of us can resist sweeping our binoculars and rich-field telescopes across the dark and bright expanses of Milky Way that flow through Cygnus like a snow-banked river at night. A main attraction of this constellation is its many open clusters, especially the bright Messier objects M29 and M39. But Cygnus has much more to offer. In fact, Cygnus is one constellation that has it all: double stars, variables, dark nebulae, gaseous nebulae, galaxies, planetary nebulae, and even a supernova remnant — and, of course, plenty of telescopic challenges.

Deep-sky observers are discovering Cygnus. Does this sound peculiar? After all, the constellation is a landmark of the late-summer sky and is awash with bright lanes of the Milky Way. Even a naked-eye view suggests that Cygnus should be a deep-sky wonderland. But only recently have amateurs pursued the individual delights that the constellation has to offer.

Most deep-sky objects in Cygnus have been overlooked because they were never mentioned by Smyth or Webb in their observing guides. Early observers paid surprisingly little heed to these objects. Smyth mentions only M29 and M39 in his famous (but now scarce) Cycle of Celestial Objects (written in 1844). Webb is almost as brief in his Celestial Objects for Common Telescopes (first written in 1859). But he says of Cygnus: “I had at one time projected a survey of the wonders of this region with a sweeping power; but want of leisure, an unsuitable mounting, and the astonishing profusion of magnificence, combined to render a task hopeless for me which, I trust, may be carried through by some future observer.”

In addition to the two open star clusters Messier cataloged in Cygnus. Smyth also called attention to the planetary nebula NGC 6826. Webb did slightly better by adding a wisp of the Veil Nebula near 52 Cygni, three clusters, and two interesting star fields (one containing the cluster NGC 6871, which he did not mention per se).

Both authors went on at length about the variable and multiple stars in the constellation, but it seems they did not spend much time at the eyepiece cxpl°^r' ing Cygnus themselves. If they had, certainly they would have written about some of the splashy open clusters scattered through this corner of our galaxy-

Later authors followed in the footsteps of those before them, and amateurs weren't directed to the lesser-known sights in Cygnus until the late 1970s when Burnham's Celestial Handbook became widely available. This work includes j_eep-^sky objects in the Swan, and there are even more plotted on Tirion's Sky _Ali_aS 2000.0.

Today's amateurs, however, are not content to use just the popular guides, frequently they roam the sky on their own, and I regularly receive mail from bservers who have “discovered” a star cluster. Most of these objects are listed in the /Vetv General Catalogue of Nebulae and Clusters of Stars. When I write back saying their cluster is in the NGC they reply,“If it’s known, why isn't it plot-_ted on the star atlases?" The answer is that the charts include only a representative sample of deep-sky objects, and most of them have been selected from the observing guides mentioned. The Tirion charts, for example, show some 2,500 deep-sky objects, which is less than one quarter of those listed in the NGC and its Index Catalogue (IC) supplement.

A superficial inspection of these catalogs suggests that only about half of the objects listed in Cygnus are plotted on the Tirion atlas. Alister Ling of Montreal has been sweeping Cygnus in search of objects not usually mentioned in observing guides. Writing in the newsletter Betelgeuse, he says that in crowded star fields he looks for hazy blobs in his viewfinder that often turn out to be magnificent clusters when seen with the main telescope. This search technique is especially useful for locating large open clusters. Ling mentions three clusters, NGC 6910.6997, and 6871, that have never been described in this column. All are plotted on Sky Atlas 2000.0, so why not hunt them down yourself?

Ling has also been using a UHC filter on his 12-inch Dobsonian at 56x.The North America Nebula (NGC 7000) “jumped out” and detail never before visible was evident. Furthermore, while casually sweeping nearby he stumbled upon the elusive Pelican Nebula (IC 5070). On another night he viewed the

The glorious North America Nebula in Cygnus may be illuminated by an inconspicuous star that is obscured by dark clouds near the nebula's "Atlantic coast." The hard-to-spot Pelican Nebula flies alongside to the west.

section of the emission nebula IC 1318 cast of Gamma (y) Cygni, the star of the Northern Cross. It appeared as a “huge sprawling region of losity split in two.”

One of the most controversial objects among amateur observers, the Nn I America Nebula (Figure 9.4) is familiar from photographs as a large diffuse o/¹¹' about 3° east and 1° south of Deneb. There has been remarkable diversity * opinion on how small a telescope can show this object visually. Some argue that thc nebula cannot be observed readily without photography, but thc region is rich that it is well worth sweeping with anything from binoculars to large tele scopes. Early telescopic observers all missed NGC 7000 because of its large size (relative to the fields of their instruments) despite its brightness. Only in the last generation or two, with the rise of rich-field designs, has the nebula become gen erally accessible to telescopes.

If observing conditions are very good, and you know what size and shape to expect, the North America Nebula can be made out easily with the naked eye An opera glass makes it more apparent, but this is not true when more powerful binoculars are used. When I was in grade school 1 had a small folding opera glass, bought for a dollar at a carnival, and it showed the nebula! Actually, NGC 7000 is difficult to see in most telescopes. With a 5-inch Moonwatch Apogee telescope you should know beforehand what it looks like, and the nebula is downright challenging in a 6-inch f/4. However, a few years ago it was brilliant when I saw it in Edgar Everhart's 11.4-inch Wright telescope, which was then located in

In northern Cygnus there is a sparse cluster that may have been spared the indignity of a “nonexistent” label because it carries the protection of a Messier number. The open cluster M39 has a distinct triangular shape. The group is 32' in diameter and 4.6 magnitude. Hence it’s within reach of the naked eye. Discovery is credited to the French observer Jean-Baptiste Le Gentil in 1750, who described it as “very dim” but visible without a telescope. In a small, low-power telescope M39 shows as a nice sparkling cluster. Smyth called it a “splashy galaxy field of stars.” Recent printings of Webb’s observing guide call M39 a "grand open cluster,” but the original never mentioned the group. It appears io have been added to the guide during a revision of the sixth edition by Thomas E-Espin in 1917.

Lc Gentil refers to thc triangular shape of M39 but orients it differently than most observers today see it. It is not clear to me, however, if his observation of the shape was made with the naked eye. Will someone try examining M39 with a range of instruments (don't forget binoculars and thc unaided eye)?

Several years ago, while observing from the Southern California desert-glimpsed a dark streak running about 5° east-southeastward from M39. 1 h^{ere |S}no doubt about a vacancy some 6' across on the east side of M39. From it ^{a na}row, dark lane can be traced eastward with difficulty for perhaps 2/ ^unt*' ¹merges with a much wider and pronounced stream that leads to the Cocoon bula. IC 5146. The obvious dark lane is Barnard 168, which is shown without label on Uranometria 2000.0 charts.

⁸ The detection of dark nebulosity depends on many factors. I lean toward using -focus instruments because my experience has shown that they tend to scat-^less I'Cht ^ancl P^rov>de ^a higher-contrast image than do rich-field telescopes. I *^e , had some dramatic views of dark objects with my old 10-inch f/8.5 ^⁸ Etonian reflector and the 12-inch f/17 Porter turret telescope in Springfield, ■708) is NGC 6819. I found this grouping early in my high-school days. It was barely detectable in my homemade 40x 1-inch refractor. According to information in Vol. 2 of Sky 2000.0. NGC 6819 is whopping 3'/2 billion years old. Thc cluster is 7th magnitude, 5' across, and contains perhaps 20 stars of magnitude 12 and fainter. The Webb Society handbook on clusters mentions several reports of nebulosity involved with the group.

In contrast with the age of NGC 6819 is M29, estimated to be only 10 million years old (Figure 9.5). While the former is nearly as old as our solar system, the latter formed not long before humans appeared on Earth. M29 is slightly larger •ban NGC 6819 and shines with a total light equal to that of a 6.6-magnitude star, doubt thc cluster can be picked out from the rich Milky Way background with *be naked eye.

NGC 6866 is about thc same size as M29 and a magnitude fainter. Catalogs list stars here. 1 have no reports of NGC 6866’s appearance in a 16-inch or larger telescope, but a 6-inch captures a nebulous glow that is probably caused by unresolved stars. In a 10-inch at 150x, the field of view is filled with sparkling starry ^exc>tement.

NGC 6894 is a planetary nebula in Cygnus, which photographs show as a fa-diamond 44" in diameter.Though it has been cataloged as magnitude I4.4 . ^1,1teurs can see it, and Agnes Wolfe writes that it seems brighter than the cat 7 J values. James Corn of Phoenix, Arizona, observed it on July 16,1952, as m ' tude 12 and large. ^a®ⁿ*'

Another object this month is the planetary nebula NGC 6826 in Cy_gnuAlthough not well known today, I found a reference to it while looking f_Or ..^S' lier mention of the Veil Nebula in an 1856 edition of Elijah Burritt’s Geo«_r„ of the Heavens. With a total light equal to a star of magnitude 8.8, in modest apertures this planetary shows a fine greenish disk about 25" across.

NGC 6826 is plotted in Norton’s with the Herschel number 73⁴. Since the pl_anetary’s 1 lth-magnitude central star was easily seen by William and John Herschel, they considered this nebula a transition object between regular p]_anetaries (whose central stars were too faint to be seen) and stars involved in diffuse nebulae. At 300x, a 10-inch reflector I had in Kansas showed NGC 6826 to have uniform light across its center. The planetary takes magnification well and is a fine object for even small apertures.

Also try finding the spiral galaxy NGC 6946 in extreme northern Cygnus. This is only 10° from the plane of our Milky Way, where it is unusual to find galaxies since the interstellar dust concentrated there obscures the light from these distant objects. Though listed as about 9' x 7' in size, this galaxy seems even less round to me. Despite the glittering foreground star field, NGC 6946 stands out well.

Unveiling the Veil

The most popular deep-sky object in Cygnus today is the Veil Nebula, though it is difficult to observe. This visually fragmented bubble of glowing gas is so large (hat most telescopes cannot contain it in one field. The challenge, of course, is seeing it at all. Over the years amateurs provided Scotty with conflicting reports as to its visibility. "While some have missed it even with large telescopes," he wrote, "Burnham has seen it with binoculars. My opinion is that the Veil is more a test of observing skill than optical parameters." Indeed, Scotty witnessed the Veil Nebula evolve from something that amateurs knew only on photographs to one they routinely studied with small telescopes. Conversations at star parties, he said, once swirled around how to view such "difficult" objects. Today, those conversations are part of amateur astronomical history, an intriguing fireside tale to share with novices, and the Veil is yet another of amateur astronomy's ever-growing list of "ex-test" objects.

The most famous celestial sights have been passed down to us throughout the centuries. The Orion Nebula is one. Another is the Andromeda Galaxy-M31, first noted in writing by the Persian al-Sufl in A.D. 964. It seems unlike that any observing guide published after Messier’s 1764 discovery of M27 fails

tion this beautiful planetary nebula in Vulpecula, and amateurs teach each nief¹¹ . ...

^1,111. _{hv n}ast observers. However, this is not the case. There are some objects 'igtill* *

¹'] ich in a sense, belong to the modern amateur.They deserve caretui attention, ' published visual descriptions are surprisingly few.

f°One such object is the Veil Nebula in Cygnus (Figure 9.6), a broken bubble of luminous gas some 2° in diameter. Although ignored by generations of telescope users in the last 30 years the Veil has progressed from a difficult test object to a

The Veil Nebula in Cygnus is believed to be the remnant of a supernova explosion that occurred at least 15,000 years ago. The filamentary remains are expanding at nearly 30 miles per second.

reasonable target for anything from binoculars to the largest amateur telescopes, h is an excellent nebula for training the eye, perhaps the most important observ-^lng “accessory,” to help us get the most out of the telescope we are using.

Astronomers believe the Veil comprises the remains of an ancient supernova. When I was young the Veil was usually listed as a planetary nebula, since the ^c°ncept of supernovae and their remnants didn’t come until the 1930s when I ^Uas ’ⁿ college. Back then the Veil was considered a unique object. Today, how-^ever, we know of several others like it, including S147 in Taurus.

William Herschel discovered the brighter parts of the nebula as he swept the ^Sky with his 18%-inch speculum-metal reflector in 1784. He included the east and ¹ sections of the loop with his class V objects (very large nebulae). In °rr_on;_v Star Atlas the westerly section carries his designation 15⁵, and it also ^ears the name NGC 6960.

The 4th-magnitude double star 52 Cygni appears to be involved with NGCftor but is actually a foreground object not related to the nebula. Incidentally, th_emistakenly identifies the star as Kappa Cygni, and other catalogs have Somet' copied the error. Even in small telescopes, 52 Cygni is an excellent double-orange and blue components, magnitudes 4.5 and 9.5, are separated by 6'/_;" ’ '^tS

The eastern loop of the Veil is NGC 6992-95 (14^s in Norton’s). Like the w_estpart, it is a strip of sculptured light about 1° long. Between the outer parts of loop are several fainter wisps of nebulosity, which show well in long-exposure ph^ tographs.Thc larger triangular piece, discovered photographically, carries nodesi nation number. Just to its east is a smaller patch of nebulosity, NGC 6979. Herschel again was its discoverer, and placed it with his class II objects (faint nebulae)

Why has the Veil Nebula been overlooked for so long? It certainly could have been seen with the reflectors and comet-seeking refractors trained on the sky back in the 19th century. I suspect there were two reasons for omitting the Veil from earlier observing guides. First, Herschel called NGC 6960 only “pretty bright” and NGC 6992-95 “very faint,” although the latter is in reality the more easily visible. Smyth may have been more responsible for diverting subsequent amateur attention from the Veil. In his Cycle of Celestial Objects he mentions only NGC 6960, and then only as an afterthought in his section on 52 Cygni. He unenthusiastically noted that the field of view in his 6-inch refractor required “considerable attention” before he was able to make out any of the nebulosity.

Other popular observing guides by T. W. Webb and Charles Barns make no mention of the Veil, although by the time of the publication of Bams’s work in the 1920s, photography had revealed the splendor of the nebula's twisted filaments.

Tn the 1940s and 50s, amateurs considered the Veil a test object. Often my mail contained bitter reports of failure to see the Veil’s faint glow. However, today it is more typical to receive detailed descriptions from confident observers. My own experience has followed a similar pattern, which I attribute to the growing education of the eye, and to knowing the Veil can be seen visually.

Richard Wilds of Topeka, Kansas, has glimpsed the three brightest sections of the Veil (those with NGC numbers) with a 2-inch refractor. In his Celestial Handbook, Burnham mentions seeing NGC 6992-95 in large binoculars. Indeed, both the east and west arms of the loop are easy in my 20 x 125 Japanese military binoculars. In a 12-inch f/5 telescope the Veil Nebula in Cygnus is beautiful-and so bright that one notes it even when sweeping. But in a 5-inch f/5 the Veil is visible only with difficulty to keen eyes. Why is this so, when the surface bright" ness of extended objects depends on f-ratio rather than on aperture?

'The seeming contradiction is removed when the eye is considered along ^w>* the optics of the telescope. Physiologists have shown that the eye can discern spot 6° in apparent diameter that is only 6 percent brighter than the backgroun • while a 2° spot must be 11 percent above background. Remember, a galaxy^vvla diameter of 3' when magnified 100 times has an apparent diameter ol 5.0 •

Hence, the greater magnification usually obtained with larger telescope (because of their longer focal lengths) may help to reveal nebulae near the ^V1S

threshold- This is contrary to popular recommendations, but 1 have succcss-⁸ iiv used high powers, especially on planetaries. Of course, when magnification

here at best, the skies are usually undistinguished. I was sweeping with Edgar gverhart’s 12-inch Wright reflector when the giant bubble-like nebula was

■ Red up. The Wright reflector has a 12-inch primary mirror and an ll/2-inch ^rector plate. This visual instrument works at f/4, and is actually a variation of (he Schmidt camera. Everhart, who discovered Comet 1964h, constructed this telescope especially for comet seeking, and mounted it atop a 35-foot tower to obtain a clear view of the horizon. With an Erfle eyepiece giving about 50x, it provided some unusual views of deep-sky objects.

While discussing the instrument’s capabilities, we wondered if it would show the two arcs of the Veil Nebula in Cygnus. We tried to find NGC 6960 (the western segment) first, because the 4th-magnitude star 52 Cygni lies on the middle of the arc. Since Everhart’s telescope is an altazimuth (for comet sweeping), he pointed the instrument by sighting with the 3x finder while I watched through the main eyepiece.

As we swept over 52 Cygni, the nebula was seen without straining. It appeared to stream across the field. In the Wright telescope the nebulosity did not look as it does in photographs, but this was still one of the most fascinating sights I have seen in a decade or more.

Later we tried for NGC 6992-5 (the eastern arc); there are no bright stars near, so we had to proceed carefully. Sweeping casually, we might have missed this object, but once it was definitely in the field it could be seen easily. Though not as bright as NGC 6960, it was sharply defined; the structure was less evident than in the companion nebula. In all.it was about as noticeable as the faint outer parts of the Orion Nebula.

New nebula filters have apparently helped many locate the Veil. A typical sighting is that by John Bartels. He set up a 414-inch f/8 surplus telephoto lens with ^a 32-mm Plossl eyepiece and Henzl 300 nebula filter at the light-polluted airfield oi Travis Air Force Base. NGC 6992-5 could be seen without the filter, but was easier with it. NGC 6960 was located only with the filter, but after knowing where and what to look for he was able to glimpse this western loop without it.

How times have changed. Now I often receive reports of the Veil being seen ^ln binoculars. Even novice observers have seen it well enough to record the east-^ern portion of this giant 2°-diameter broken loop as brighter than the western ^s,rand passing near 52 Cygni. At the 1984 Texas Star Party, Lee Cain with his 17-*^nch Dobsonian binoculars saw the Veil so bright that he almost “feared it would ?*^ln my dark adaptation.” Bryce Heartwell of Alberta, Canada, considers the ^ei “totally beyond description” as seen with his 17-inch reflector. When he ^added a Lumicon UHC filter to the system, “the Veil showed as much detail as ^Photographs.”

1 have also heard from experienced observers that the Veil can be seen with the naked eye through a UHC nebula filter. This is amazing when you consider that only a few years ago most amateurs thought of the Veil as one of the sky's great telescopic challenges. Dozens of observers have written me enthusiastic letters about the Veil’s appearance in telescopes equipped with UHC filters. Both the eastern (NGC 6992-95) and western (NGC 6960) sections of the nebula show delicate filamentary structure.

The following report from Joanne Konst of Kenton, Ohio, will be of interest to everyone who plies the heavens through city lights. Her house lies just two blocks from the center of town on a corner lot bathed in the glow of street lights. From her second-floor balcony she scans the sky with a 10.1-inch Dobsonian reflector and a battery of Lumicon filters. “The Veil Nebula in Cygnus reveals many features,” she writes. “NGC 6960 on the western edge was difficult without the filter due to glare from 4th-magnitude 52 Cygni. The eastern section of the loop. NGC 6992, is very detailed. While I can see it without a filter, using one enhances the view and brings out faint details. The edges look like ragged cotton, and 1 can see many delicate filaments. NGC 6979, as well as several other patches within the confines of the loop, are visible with a filter.” Perhaps her report will inspire others to try their telescopes from less-than-pcrfect observing locations.

The Mystery of NGC 6811

Scotty claimed that in spite of the electronic revolution sweeping amateur astronomy, we should remember that the eye itself performs extensive image processing. As an example, he introduced us to the open cluster NGC 6811, a small group of stars in Cygnus's northwest wing. At a glance, the cluster appears rather innocuous, containing about 70 stars and shining near 7th magnitude. Indeed, when Scotty looked at it in his youth he recalled it to be "an unimpressive, nondescript group-But a letter he received in the mid-1980s from amateur observer Tommy Christensen not only changed his view of the cluster, but set him hot on the trail of a new and wonderful mystery. Yet Scotty was magnanimous; he resisted the temptation to g°

Several years ago I received a letter from Tommy Christensen, who lives in Odensa, Denmark, and observes with a 3Z-inch refractor. Along with a _crjption of M33 and the Veil Nebula was a brief note about the open star clus-NGC 6811 in Cygnus (Figure 9.7). He called it one of thc most beautiful clus-^te he has seen and mentioned "a dark band about 5' thick running through the ^|L1jdle of the cluster, not completely without stars, but nevertheless conspicuously dark." He also likened it to a "smoke ring" of stars.

My recollection of NGC 6811 was of an unimpressive, nondescript group of stars near Delta (5) Cygni. A quick look through my notes showed no reference to a ring of stars. Furthermore, I checked observing guides and my file of reports from amateurs. Again, nothing unusual was mentioned. A 6-inch instrument will show some 75 faint stars shimmering inside an area 15' across. It reminds some amateurs of an opera-glass view of the Beehive Cluster in Cancer.

A print from the photographic Ross-Calvert atlas did, however, suggest that GC 6811 has a dark center. But the cluster is not well resolved on the print, and ¹¹ s diffi_cu]t to compare a blue-light photograph with what is seen visually. I could ^ave waltzed out to my telescope and settled the matter, but I thought it better ^to solicit comments from readers; this I did in my September 1985 column. I was P^Urposely cryptic, asking only if anyone had seen something “unusual" in NGC

Observers took the bait! In poured scores of letters. It’s quite impossibl tell just how many people reported observations. Some letters contained ments from a single observer, while others offered the consensus of as many⁰¹' 20 amateurs at a star party. ’ ^as

The reports came equally divided in thought. One group assumed the clust formed some kind of figure. There were letters extolling bells, butterfli^ dinosaurs, and a pair of fighting peacocks, and one delightful comment from * person who saw “Nefertiti’s head-piece." Several of those who wrote saw th_rc ? leaf clovers, and one amateur went whole hog for a four-leaf clover (his friend however, saw a frog!). Using several 17-inch telescopes at the 1985 Astrofest ’ Wisconsin, I saw the cluster as either a butterfly or rotifer outline.

The other camp comprised observers who saw a dark center in NGC 6811 They also usually mentioned dark lanes. One even used Christensen’s term “smoke ring.” A young observer from Ohio simply said “stars in a ring."

This is a beautiful, albeit minor, example of how people see things differently Everyone was looking at the same cluster, but because of experience, conviction or psychological factors, each saw it in a different way.

I expected some correlation between telescope aperture and visual description. To some extent this was true. The largest telescope used to report a “dark center” was an 11-inch reflector. The smaller the telescope, however, the more pronounced the feature appeared. With apertures of 16 inches and larger, the dark center just doesn’t seem to show. So how can we say what is the “real”

Then I got a letter from Marton Konecny of Czechoslovakia. He observes with a 2’/2-inch Zeiss refractor and magnifications from 14x to 140x. While Konecny comments that Americans might think this a small instrument, it is about the standard amateur telescope in his country. He too saw NGC 6811 as a clear cut ring of stars with no hint of the butterfly pattern I had once suggested in an earlier column. I only hope he gets a chance to view through a 16-inch someday! Konecny sent a drawing of NGC 6811, which is unusual in that it records a glow around some of the stars. Have others noted this?

Hunting Cosmic Pearls in Aquila

Aquila, the Eagle, soars highest on cool September evenings. Its brilliant ice-blue gem, Altair — the southern star of the Summer Triangle — adds a flash of sparkle to the lacy boundaries of the Milky Way that brush past this celestial raptor. Despite its prominent placement, Aquila contains some interesting objects, but surprisingly few are truly spectacular. Aquila does have a bounty of planetary nebulae, however, which are within the reach of amateur-sized telescopes. Until Scotty began introducing them to his readers, these cosmic pearls, as he referred to them, were largely ignored in the popular literature. Here Scotty introduces us to several planetaries in the neighborhood of Altair. Many of them have gone unseen, becaus

|,_ey are not plotter! on some popular sky atlases, such as Wil Tirion's Sky/tt/as 2000 O' Furthermore, published magnitudes for faint planetary nebulae are usually Fjj_snially underestimated, causing many amateurs to shy away from them. But times, eqU'P^ment' ^ar*d knowledge continually change, and Scotty was right on top of I _ew observing trends, as we shall see.

September brings a slack tide of celestial treasures. As twilight gives way to dark, the golden sands of Sagittarius remain in the south and the Northern Cross in Cygnus still floats overhead. But nothing very new or dramatic is coming ^UP >^{n t}*^{qe easL} Th°^{sc w}h° observe late into the night often have their first taste of the crisp autumn air that will follow as days grow shorter. And just before dawn the luminous cone of zodiacal light rises from the eastern skyline. It is one of the most pleasant times of the year to be out under a starry sky.

The evening meridian is dominated by the three brilliant stars of the Summer Triangle. At its southern apex is lst-magnitude Altair, a celestial neighbor located only 16 light-years from Earth. In my mind’s eye I see Altair wrapped in a galactic blizzard of tiny luminous spheres. We know them as planetary nebulae, pearls on the grand scale of the galaxy.

Until a decade or two ago most deep-sky observers concerned themselves with only the few bright planetaries large enough to show some detail in small telescopes. Objects like the Ring Nebula in Lyra and the Dumbbell in Vulpecula were standard fare at summer star parties. Although a handful of amateurs observed others, hardly anyone dreamed of searching for the tiny glowing gas bubbles scattered around Altair. Indeed, few even knew they were there!

Times have changed. Today’s observers have access to larger telescopes. They have better catalogs of deep-sky objects, and, more important, better star charts. They also have nebula filters. Today’s observers eagerly venture into cosmic depths that their counterparts of a generation ago hardly knew existed.

Perhaps the best place to begin our search for Aquila’s planetaries is on the pages of Uranometria 2000.0.1 consider this atlas among the best ever made for observers. The charts have a generous scale, with 1° equal to about % inch. This is roughly the same scale as the finder charts that have endured through more than 80 years of use by the American Association of Variable Star Observers. Plotting a position on the Uranometria 2000.0 charts is easy because epoch 2000.0 grid lines are shown for every degree of declination and, except near the ^celestial poles, for every four minutes of right ascension. Stars are shown to ^about magnitude 9.5, the average limit for a 2-inch finder, and more than 10,000 d^eeP-sky objects are plotted.

But there’s more to deep-sky observing than just knowing the location of an °hject. Without such basic information as its size and brightness, we could sweep °^Ver °ur target and not even know it. A lOth-magnitude planetary that’s 5' in ^lameter is going to look a lot different from one only 5" in diameter. To that . ^Cnd’ observers will welcome Uranometria 2000.0's companion volume, The

Deep-Sky Field Guide by Murray Cragin, James Lucyk.and Barry Rappap_Orj I gives basic information about all the deep-sky objects plotted in the atlas. [| • arranged by chart number, making it particularly useful in the field, since inf *^Smation about all the objects on one chart can be found on one page (or sev ' adjacent pages). ^al

Altair is on chart 207 of Uranometria 2000.0. The corresponding page of 77 Deep-Sky Field Guide lists a dozen planetary nebulae. Of these, only three * front the NGC; the rest are from more modern compilations. Since almost al] th NGC objects were discovered visually, they are generally the easiest to see amateur telescopes.

One of the objects to which Smyth calls attention in his classic A Cycle of Celestial Objects is NGC 6804. It is small, only about 1' in diameter (Figure 9 8) He comments that in “very powerful" telescopes NGC 6804 appears fan-shaped William Herschel, who discovered the object, thought he could resolve it j_nt₀

Seemingly lost among the multitude of stars in the Aquila Milky Way is NGC 6804, a planetary nebula some 4,700 light-years distant.

component stars and thus placed it in his class VI (very compressed cluster of stars). Norton’s Star Atlas once carried the Herschel number 38⁶ for this object, although we now know it to be a planetary nebula.

Careful examination of NGC 6804 with different apertures would make an interesting project at a star party of serious observers. It is about 30" in diante ter (the minimum size of Jupiter) and 12th-magnitude. Its visibility depends heavily on sky conditions. I have seen it on several occasions here in Connection¹with a 4-inch Clark refractor, but not in recent years with our increasingly polluted skies. My observing notes from the 1950s in Kansas always call the pl^jnetary “easy” in a 10-inch reflector.

0ne of the great pleasures of deep-sky observing is the individuality that cer-in objects acquire in the eyepiece. I'm always delighted to learn that someone _ees an object in a new perspective. One such example comes from Robert [vfoseley of Coventry. England, who tracked down NGC 6804 while testing a new |0-inch f/6 reflector. His best view was at 120x. He writes,"It gives the impression fa highly condensed but partially resolved cluster. It is a faintish oval nebulosity with a 12th-magnitude star toward its northeast edge. With averted vision at least one other star could be seen superimposed on it." Moseley questioned the 13th magnitude I had given for NGC 6804 in an earlier column. Published magnitudes for planetary nebulae cause many disagreements, and I believe it is best to slightly mistrust all of them and to record your own magnitude estimates with your notes.

Just 50' to the north is another planetary. NGC 6803 is only 6" across and 11th magnitude, which should give it a much higher surface brightness than NGC 6804. Oddly enough, however, my observing notes suggest that I have had a more difficult time with this object.

Most of the other planetaries on Uranometria 2000.0 chart 207 are less than 10" in diameter. As such, they appear starlike at the low magnifications most observers use for hunting down objects. But planetaries emit most of their light at a few discrete wavelengths, especially two emission lines of doubly ionized oxygen near 5000 A. Some enterprising amateurs have attached small, narrow prisms to telescope eyepieces to distinguish between faint stars (which have their light drawn into short streaks) and the tiny planetaries (which remain starlike).

Another trick is to use a nebula filter (such as Lumicon’s O III filter) that isolates the oxygen emissions. The narrow passband of this filter dims surrounding stars because it blocks most of their light while leaving the planetary’s brightness relatively unchanged. Repeatedly flicking the filter between the eye and eyepiece causes the planetary to blink, making it easy to identify which “star” is the nebula.

If you are prepared for the challenge, here are three planetaries that will test your abilities. I have never seen any of them. Furthermore, because the light of a planetary is confined to a few wavelengths, I question how its brightness determined by conventional methods (usually involving photography) compares with what the eye sees.

PK 52-2.2 (the designation is from the Catalogue of Galactic Planetary Nebulae by Lubos Perek and Lubos Kohoutek) is less than 10" across and 12th magnitude, 'rhe Deep-Sky Field Guide notes that it has a "ring structure.” If you ^Can locate this object, its appearance will serve as a reference for the other small Planetaries. It has a 14th-magnitude central star.

PK 45-2.1 is less than 5" across. Although it is listed as visual magnitude 12.7, ^lls smaller size should give it about the same surface brightness as PK 52-2.2 if you use very high power. It is listed as having a “stellar image.”

1 suspect that the most difficult of the three is PK 52-4.1, which is less than 10" ^ln diameter and magnitude 13. If you succeed here, you can test your skill on sev-^eraI even fainter planetaries listed in the Deep-Sky Field Guide.

Ast = Asterism; BN = Bright Nebulo; CGx = Cluster of Goloxies; DN = Dork Nebulo; GC= Globular Cluster; Gx = Goloxy; OC = Open Cluster; PN = Planetary Nebulo; * = Stor; * * = Double/Mulliple Star; Vor = Vorioble Sfor

OCTOBER

The Great Square of Pegasus

Compared with the brilliant, star-studded sky of winter, the autumn sky is but a vast celestial prairie of feeble suns. Even Pegasus, whose Great Square is the season's hallmark asterism, appears drained of starlight to the naked eye. And though the Square is one of the most familiar of all star patterns in the sky, it is also one of the more difficult for beginners to find, because of its large size. On a star chart, the Square appears so small. But Pegasus is enormous. It is the seventh-largest constellation, covering 1,121 square degrees of sky. Yet, despite this size, Pegasus is not a cornucopia of conspicuous deep-sky objects. In fact, it has only one Messier object, the globular Ml 5. Scotty, however, was a digger, and you could leave it to him to find any telescopic nuggets. "Whether you use a 2.6-inch refractor or a 29-inch reflector," he wrote of Pegasus, "there is plenty to delight your eye."

October is a most auspicious month for amateur astronomers. The summer haze and humidity have given way to cooler days and crisp, clear skies at night. Darkness comes earlier, dewing of a telescope’s optics is generally less of a problem, and the sky is not so jammed with star clouds that confusion rules.

The Milky Way stretches from east to west across the northern star patterns, but here we are looking in the direction approximately away from the center of the galaxy. Star swarms marking the galaxy’s plane are thinner, and it is easy to star hop and make finder searches for objects embedded within them. Some of the most beautiful sights for small telescopes are in and around this corner of the Milky Way.

Overhead the Square of Pegasus dominates. As a small boy I thought of the Oreat Square as a baseball diamond where the Norse gods Odin and Loki pitted their mythical teams against one another — stray meteors were pop flies and ^cl°uds meant the game was called on account of rain. To my father’s dismay, I ^al»ays rooted for Loki!

Only schoolchildren and a few ROTC veterans of the U. S. Army and Navy are familiar with the old Star Atlas and Workbook of the Heavens, published by American Education Publications. Although long out of print, the 32-page booklet was used heavily in schools during the late 1960s and early 70s. It container a novel method for learning the easily recognized constellations. Rather than having the Big Dipper as a starting point, it had a key constellation for each season: Leo, Scorpius, Pegasus, and Orion for spring, summer, fall, and winter respectively, 'rhe reason was simple. As the Dipper's position around the p₀|_echanges with the season and time of night, its pattern sometimes becomes difficult for beginners to locate.

Tests of pattern recognition showed that difficulty can arise if a star chart i_srotated just 15° with respect to the sky. Furthermore, the concept of seasonal key constellations grew out of research done during World War II at the celestial navigation school at Selman Field in Monroe, Louisiana; this system produced the best constellation learning among the 500 cadets tested. The key asterism for fall was the Great Square of Pegasus (Figure 10.1). While none of the Square’s stars are 1st magnitude, it dominates October’s star-poor evening sky. Counting the stars within the Square is a good indication of the sky's limiting magnitude. For example, if you see 13 stars you are reaching magnitude 6.0.

How many naked-eye stars can be seen within the Great Square of Pegasus? A quick look at the Skalnatc PlesoAr/as of the Heavens suggests more than 100-but many of the stars plotted are below the traditional 6th-magnitude naked-ey^elimit. However, with dark skies and good transparency, many observers report glimpsing stars as faint as 7th magnitude. And in 1901, the Lick Observatory astronomer Heber D. Curtis found that, by shielding off the light of the sky a taking other precautions, he could just detect stars of magnitude 8.3.

One answer to the Pegasus question comes from John Bartels, who counted 38. . mentions, however, that some high cirrus clouds may have interfered.This sug-sts his limit was magnitude 6.6. If you push your limit to magnitude 7.0. then 70 ftars should be visible.

j^_ow many deep-sky objects are visible in Pegasus? The present-day list in Robert Burnham’s magnum opus, Burnham's Celestial Handbook, carries 23. Moreover, in the text there is mention of the famous “Stephan’s Quintet," which ffectively adds five more galaxies to the list. During the years of writing this column I have discussed 16 objects in Pegasus. Despite the apparent paucity of deepsky targets, the number of objects given in the various handbooks is appropriate for typical amateur instruments in use at the time the books were published. However, in the years that have passed since Burnham’s complete work became available, the size of amateur telescopes has increased greatly. The rise of the Dobsonian reflector has been a major reason.

Telescopes of 17-inch aperture are now off-the-shelf items of modest cost.There are a dozen or more amateur groups in the United States that either now have or are completing instruments with apertures of 24 inches or more. Such light-gathering power brings within reach of the backyard observer virtually every deep-sky object in the NGC and IC compilations. Titus the Great Square of Pegasus alone contains more than 100 suitable objects.

Not all the objects are easily located. So, if you do your searching with a finder, it is important to know the size of its field of view. Use a star atlas to determine the distance from an easily identified star to the object of interest and then offset from the star with the finder. You can try this method on NGC 16, a tiny galaxy r/2⁰ south of the bright star Alpha (a) Andromedae at the northeast corner of the Square of Pegasus. (Although the star is officially in Andromeda, it is sometimes marked on charts as Delta (5) Pegasi, which refers back to when some stars were shared by the two constellations.)

If your finder has a 3° field, and you place Alpha Andromedae at its northern edge, NGC 16 should be just about centered. This elliptical galaxy is only T in diameter and 13th magnitude. With a 6- or 8-inch aperture, scan a 30x or 40x field with your eye for an object that is a bit too big to be a star. It is best not to sweep lhe telescope for this galaxy since an object this faint will probably be rendered invisible if the field is moving. Once you suspect you have the galaxy, higher magnification can be used to confirm it.

Another good star from which to begin a search for galaxies is Alpha (a) Pegasi ^at the Square’s southeast corner. Just about 3° to its south is NGC 7479. a barred ^sPiral that appears just over 3' long and a bit brighter than 12th magnitude (Figure ^•2). If you have a motorized mount, you can also set on Xi (£) Pegasi and wait minutes for this object. If your eye is properly dark-adapted, the galaxy should be visible in even a 3-inch telescope, but a 6-inch is better. A cloth over your head ^and the eyepiece gives good protection from stray light. I have seen it easily with

4-inch Clark refractor, but with this small an instrument it is not possible to see ^anV detail. On the other hand, the 12-inch f/17 Porter turret telescope at Stellafane

Just about 3° south of Alpha (a) Pegasi is NGC 7479, a very asymmetric spiral galaxy with a bright, long bar and looping spiral arms. Star formation occurs over the entire visible portion.

in Springfield, Vermont, offers a more interesting view. At 300x the central bar is obvious, and there is a hint of a spiral arm at one end.

A 12-inch f/5 reflector set up near the Porter telescope did not offer as good a view of NGC 7479 even though I thought the mirror was good. It may have had something to do with the longer focal length of the Porter telescope, or a better eyepiece. The importance of fine-quality eyepieces has been overlooked by many amateurs. Recently several types of expensive but very high-quality eyepieces have come on the market. Judging from my mail, it seems that these oculars distinctly improve the deep-sky performance of a telescope. Objects once considered only within the reach of large amateur instruments are being seen in smaller telescopes equipped with fine eyepieces.

Several other small galaxies lie near Alpha Pegasi. NGC 7448, an 11.8-magni-tude spiral located I/2⁰ northwest of the star, is about 2' long and half as wide. Like NGC 7479, it is readily seen with the 4-inch Clark. However, increasing the aperture does not improve the view other than to make the object appear brighter. My old 10-inch reflector in Kansas simply showed it as a featureless glow.

NGC 7454 is a challenging galaxy, located about /2⁰ northcast of NGC 7448. Although more than a magnitude fainter, its surface brightness appears nearly the same owing to a diameter of just 0.5'. At low powers NGC 7454 is easily mistaken for a faint field star. It, too, appears quite featureless even with a large tele scope. A few years ago I had a peek at it with a 16-inch reflector, and though ¹was easily seen, no detail was visible. For an instrument of this size, there exist

_qrly a dozen more galaxies in the immediate area — all below thc 13th-magni-* . limit for galaxies plotted in Tirion’s Sky Atlas 2000.0 but listed in thc Revised General Catalogue of Nonstellar Astronomical Objects (RNGC).

magnitudes listed for galaxies are often deceptive to the amateur observer the visibility of one of these dim glows depends on its size and shape, in jition to its overall brightness. A 4-inch telescope can sometimes reach 12th-'* nitude stars, but this does not mean that it can show 12th-magnitude galaxies. _o facts might encourage the amateur. Almost all the entries in the NGC were discovered visually. In addition, long practice improves the ability to detect faint objects.

Here are some test galaxies of differing difficulty, located in Pegasus. Much of the difficulty in finding a faint object is avoided when one knows just where to look among the field stars. First look for NGC 7678, a 1.7'x 1.1'spiral; I saw it with _a 10-inch in Kansas and it is easy in the 20-inch refractor of Van Vleck Observatory. NGC 7469 is a 1.3' x 1' spiral and slightly fainter. I could not find it with a 6-inch refractor but years back I viewed it in a 13‘/2-inch reflector. For a very demanding test, try NGC 7619 and 7626, a pair of tiny elliptical galaxies of about the 12th magnitude. In the 20-inch they could be seen with some difficulty, but a 4-inch refractor was insufficient on a good night. What is the smallest aperture with which you can fish out this pair?

Can someone explain NGC 7772, which Norton’s atlas shows inside the Great Square of Pegasus? It is missing from the Atlas of the Heavens, but the NGC describes it as "a cluster of scattered stars of about 10th magnitude.” However, I see no particular concentration of stars in its place. The original discovery seems to have been by Sir John Herschel.

Finally, a bit of observing trivia: who knows how close on the sky the first and last entries in thc NGC lie? NGC 1 is a 12.8-magnitude (my estimate with a 10-inch reflector) galaxy in Pegasus. The last entry in the original 1888 catalog is NGC 7840, but a 1973 revision by Arizona astronomers Jack Sulentic and William Tifft states that the object was not found on photographs made with the 48-inch Schmidt telescope in California.Thus, the last real object appears to be NGC 7839 —■also in Pegasus and at essentially the same declination as NGC l.The positions in the original catalog place NGC 7839 only 5.6' southwest of NGC 1. However, NGC 7839 is very faint (it does not even have a listed magnitude in the revised NGC) and may be well beyond the reach of most amateur telescopes.

Using the list of objects in Vol. 2 of Sky Catalogue 2000.0, which is well suited f°^r amateur instruments. I find the closest readily observable object to NGC 1 is UC 7819, a faint galaxy in Pegasus. It is about 3.8° north of NGC 1.

Thus, NGC 1 and NGC 7839 are the first and last valid entries in the NGC, and ^{11 s}° happens that these galaxies are separated by less than 6' on the sky. NGC 1 about 1' across and, by my estimate, about magnitude 12.8. It forms a pair with . 2, which is more than a magnitude fainter and 2' to the southeast. NGC 7839

Although NGC 7840 is technically the last entry in the NGC, it app_arcdoesn't exist even though it was reported by such an outstanding observer Albert Marth, who worked with William Lassell’s 48-inch reflector on the i i ^3Sof Malta. ^and

Two Spectacular Autumn Globulars

"Some deep-sky objects are remembered for their beauty, others are cherished f_Ortheir scientific importance," Scotty wrote. "Some are sought out as test objects to establish the excellence of a telescope, observer, or atmospheric condition, and there are those best known for their unusual features." Finding any one object to meet all these criteria would be hard, but two autumn objects fit many of the categories — the splendid globular clusters M15 in Pegasus and M2 in Aquarius For many observers, globular star clusters encapsulate all that is stunning and test-worthy. For instance, both M2 and M15 hover at the limit of naked-eye visibility, presenting an enjoyable challenge for dark-sky observers. Resolving the cores of these globulars with small telescopes is equally challenging, no matter where one lives. And their visual appearance has sparked controversies that have persisted for decades. For instance, are their disks colored? Are they marred by dark lanes and patches? Scotty believed that observers had overlooked such features for nearly a century.

The archetype of modern observing handbooks for amateurs is William H. Smyth’s Bedford Catalogue. When this English observer prepared his classic as the second volume of A Cycle of Celestial Objects in the early 1840s, he mentioned only two deep-sky objects in Pegasus.This is unusual considering that it is the seventh-largest constellation. There is little doubt that Smyth was acquainted with more “nebulae” in Pegasus, for he had access to earlier catalogs, especially the great works of the Herschels. However, he chose only those that he felt amateurs would be interested in viewing.

In 1859 Thomas W. Webb published Celestial Objects for Common Telescopes. In many respects it relied heavily on Smyth's work. Webb originally included only one deep-sky object for Pegasus. He added a second in later editions, but it was different from Smyth’s selection. Other observing guides added more.

All handbooks from the time of Smyth agree on including one object in Pegasus — M15 (Figure 10.3). Although Messier first saw it in 1764, it had been discovered by Jean-Dominique Maraldi in 1746. (Incidentally, some sources incorrectly state that Maraldi discovered M15 while searching for De Cheseaux’s comet of 1746, when it was actually M2 that he found then )

M15 (also called NGC 7078) is easily located about 4° northwest of Epsil°ⁿ(e) Pegasi. It is one of the few Messier objects easily picked up by sweeping-Make the first sweep northward from Epsilon by turning the declination axle-and stop after going about 5°. Now move one field to the west and move so I,_v the same amount. Repetition of these steps, as if mowing a lawn, should bring jje telescope across the field of M15 in a short while. This globular is unmistak-ble because there is a 6th-magnitude star beside it in the same low-power field. Recording to Sky Catalogue 2000.0, M15 is about 12" across, with a V magnitude _of 6 35- Th’^s magnitude, derived from photoelectric measurements, is close to hat th^{e e}Y^e sees.Therefore, Ml5 should be visible to the naked eye. Remember, though, that eyes vary from person to person, not to mention over time (I see red tars brighter now than I did years ago), so the actual perceived brightness of an object is never completely fixed. One way to improve the chance of seeing it without optical aid is to look through a long cardboard tube painted black on the inside. This will cut down the often unappreciated flood of sky brightness and improve your magnitude limit.

The view of M15 is impressive with anything from binoculars to the largest telescope.Telescopes of 4-inch aperture and less will not resolve the core of Ml5. Mv 4-inch Clark refractor at 40x shows M15 as a slightly oval disk, more luminous in the center, with edges just beginning to break up into individual stars. Increasing the magnification enhances the view, and at 200x stars at the center

The core of globular cluster M15 in Pegasus is extremely densely packed, suggesting that a sudden, runaway collapse due to the gravitational attraction of many stars in a small region of space may be occurring.

°f the cluster start to be resolved. I once succeeded in resolving the core with my °>d 10-inch f/8.6 reflector and a low-power eyepiece coupled with a Barlow lens Y'elding 200x. However, the same ocular combination on a 12-inch f/5 instrument did not break the center up into individual stars completely. I have always ^rec°mmended using a Barlow for boosting magnification. Eye relief is better, and dust on the ocular scatters less light than if an equivalent high-power eye-P*^ece is used alone.

I had an astounding view of the cluster with a 17-inch reflector and 9,_n, Nagler eyepiece. M15's stars nearly filled the field. I also remember vivid] ₍breathtaking view of this globular cluster many years ago with the 36-inch ref]_e(;^ator at Steward Observatory in Arizona, which showed stars splashed all over th field of view. Stars literally erupted in the eyepiece field, and with averted visi₀^Cthe cluster's stellar population seemed to double.

The outer reaches of the cluster arc so frayed that the eye cannot tell where ' ends. Smyth commented on star chains radiating outward from the cluster i have confirmed this appearance with the 4-inch Clark refractor at my Joseph Meek Observatory. But 1 find more interesting a remark by T. W. Webb who wrote, “Buffham, with 9-in. spec, finds a dark patch near the middle, with 2 faint dark 'lanes’ or rifts, like those in M13, unnoticed by h.or D’A. "Are we to believe that a 9-inch speculum-metal mirror could show features that were missed by the skilled eyes of John Herschel (h.) and Heinrich d'Arrest (D’A.), or are these dark markings just an illusion? My notes also do not mention any of the dark patches suspected by John Mallas when he observed with a 4-inch refractor. Perhaps some amateurs would like to check on the existence of such features.

For years, dark lanes reported in the Hercules globular M13 were also thought to be illusions, but several years ago they were rediscovered by amateurs and are now common fare at star parties. Visibility of the M13 markings depends on telescope aperture and magnification. Perhaps those in M15 are similar. October is prime time for amateurs to give M15 a good working over with different telescopes under a wide range of conditions. Although I encouraged amateurs with 16-inch and larger instruments to follow up these reports. I’ve never had the patch or lanes confirmed. It’s worth pursuing because professional astronomers have found dust clouds in the southern globular NGC 362. Although their work is based on CCD observations and image processing, it seems reasonable that some dust clouds could be visible to the eye.

In the past I have mentioned a planetary nebula within M15. Known as Pease 1 and located on the cluster’s northeast side, it was discovered in 1927 on photographs made with the 100-inch reflector at Mount Wilson Observatory. I had always considered this tiny (1") 14th-magnitude object probably beyond the reach of any amateur telescope, but recently three observers sent interesting reports. All used the Lumicon O III filter to locate the planetary with the blinking method. By flicking the filter in and out between the eye and eyepiece, the planetary appeared to blink relative to the stars.

The distance to M15,40.000 light-years, is similar to the 50.000 value listed for M2, our other spectacular autumn globular (Figure 10.4). One way to pick up J* is to aim your telescope a quarter of the way from 3rd-magnitude Beta IP Aquarii to 2nd-magnitude Epsilon (e) Pegasi. You will find a great glowing heap of stars, with the brighter ones sprinkled like stardust over a disk 10 °^racross. M2 has a total visual magnitude of 6.3. Thus one would expect it to be ble to ^t*^{ie na}*^<e^ ^ey^{c un<}Jer excellent observing conditions, but such sightings are uncommon.

-The famous variable star-observer and comet discoverer Leslie Peltier finds a more difficult object for the unaided eye than M33, the large spiral galaxy in Triangulum. In the clear dark skies over the Yucatan Peninsula in Central ^nierica I could view M33 directly, but M2 required averted vision before it could be glimpsed directly. But I have seen M2 often with the naked eye in Kansas. Missouri. Arizona, and even from the bayous of Louisiana. M2 is one of •hose happy objects that are a delight in any size instrument. Binoculars give enough detail to keep the amateur interested, while the view I once had with Wesleyan University’s 20-inch Clark refractor was spellbinding.

Fully 37 percent of the light from the globular cluster M2 in Aquarius comes from the stars populating the cluster's central square arcminute.

M2 was discovered by Maraldi in September 1746. Because he could not resolve the glow into stars, he initially mistook it for a comet. Indeed, when Charles Messier first saw M2 some 14 years later, he did not resolve it into stars ^e>ther and likened the cluster to the nucleus of a comet. Interestingly, in today’s 'nstruments, 13th-magnitude stars on the fringes of M2 can be glimpsed in an 8-^lnch, but in a 4-inch the cluster is generally unresolvable and condensed like a ^c°rnet. In fact when a number of observers independently discovered Comet Kobayashi-Berger-Milon (1975h) in the same field as M2, it was not possible to ^tell the globular from the comet until the comet’s motion tagged it.

Smyth mentions that an observer named Samuel Vince viewed M2 with miani Herschel’s 40-foot reflector in 1779 and saw tiny stars right to the cen-

ter of the cluster.Today, a good 12-inch telescope can resolve M2 even to its _cas I have seen it with the Porter turret telescope at Stellafane. Using this in ■< ^C’ mcnt I find John Herschel’s description of M2 most suitable, for he called cluster “a heap of fine sand." ^e

Two observations of M2 in recent times warrant attention by amateur Kenneth Glyn Jones in his Messier's Nebulae and Star Clusters mentions a f_aj_n^ greenish-blue glow around the cluster under certain observing conditions j_oj_lnMallas, who used a 4-inch refractor, reported seeing a dark lane crossing th northeast corner of the cluster. Perhaps some astrophotographer could invest; gate Mallas’s dark lane by taking a set of different exposures. By the way, Steve Coe of Glendale. Arizona, writes that M2 has “lovely chains of stars meanderin outward from the core, and several dark lanes are visible.”

Sweeping Through Sagitta

After darkness falls in mid-October, look halfway up the sky, just west of the meridian and just north of scintillating Altair. There you will see four close-knit stars marking out Sagitta, the celestial Arrow. Sagitta is one of the best known of the very small constellations, mainly because amateurs use it as a guide to the famous Dumbbell Nebula in dim Vulpecula. Although Sagitta is small (its official boundaries have varied over time), it now covers an area of 80 square degrees, making it the third-smallest constellation. The constellation lies in a rich section of the Milky Way and hosts a bounty of celestial riches, including the once mysterious and ambiguous star cluster M71 and a neglected open cluster known as H 20. "So sparse is this cluster," Scotty wrote, "that without careful positioning of the telescope it is easy to overlook."

As a child I would stand outside on autumn evenings and fantasize about the constellations. I would watch as the horse-archer Sagittarius shot a golden arrow at Scutum (Sobieskii’s Shield). The arrow would strike the top of the shield, tearing a great hole in it, and the fragments would fall back together as the arrow-shaped open cluster Mil.The arrow would then soar upward into the star clouds, where it would hang poised for another target in thc Milky Way or perhaps another galaxy or even some imaginary other universe.

Now, over half a century later, the arrow Sagitta (Figure 10.5) still hovers where I saw it as a child. When first described by Eratosthenes, this little con stcllation consisted only of a group of stars running 4° from cast to west. By 'he 19th century, map makers had enlarged its area to 10°, and when 'he International Astronomical Union reorganized constellation boundaries in 'he 1920s Sagitta’s territory grew to 20° across, where it will probably remain.

As old as it is, however, Sagitta seems to be little observed. It lies in a Milky Way star cloud, so the field is swamped with faint stars. The a/ ’ , describes numerous NGC objects in this part of the sky as “nonexistent-pjovvcver, this usually means that the object, though recorded by earlier _obs^crvers' ^{was not} f°^und ^on photographs examined by thc authors of the Rpj(jC- As many amateurs know, a group of stars that stands out as a cluster in telescope can become lost on a photograph, especially if the field is full of faint background stars. An interesting project, though one with little promise of fame, _ould he to search visually using, say, a 12-inch telescope, for the objects listed _s nonexistent or “not found” in the RNGC.

The constellation Sagitta straddles the Milky Way and points to several deep-sky wonders. South of it lies the constellation Aquila, with the bright star Altair.

One cluster not easily overlooked in Sagitta is M71. Indeed, it was visible with my childhood 1-inch 40x refractor. You will find it south of the center of a line running between Gamma (y) and Delta (8) Sagittae, about 20' northeast of 6th-magnitude 9 Sagittae in the shaft of the arrow. I have always wondered why Messier saw so little in the cluster (Figure 10.6). He described it as very faint with ⁿ° stars and wrote, “The least light extinguishes it.” Maybe it was a poor night ^when he examined M71, which was brought to his attention by Pierre Mechain ^ln ^80 (after being discovered by earlier observers). On fainter objects, Messier ^Usually saw more detail.

With medium magnification, my 4-inch Clark refractor shows individual stars ^ather uniformly distributed across the 8th-magnitude cluster. M71 has been

Once an object of contention, M71 in Sagitta is now recognized as a loose globular cluster rather than a rich and remote galactic cluster.

called both an open and a globular cluster. The early 20th-century dean of visual observers, E. E. Barnard, noted that M71 looked like a globular cluster in his 6-inch refractor. And the French observing handbook Revue des constellations gives this description: “In 10 x 50 binoculars and a 2'A-inch refractor at 20x, well seen, large and diffuse. Globular appearance, detached in a rich field, unresolved, with 3’Z-inch refractors at 30x to 45x. Fine cluster 6' by 5', some stars visible with an 8-inch reflector (150x); about 20 stars of magnitude 12 and fainter, on an irregular milky background, in a 12/2-inch at 80x.”

My old 10-inch f/8.6 reflector, which, with its %-inch-thick plate-glass mirror, was essentially a forerunner of today’s Dobsonians, gave a magnificent view of M71 at lOOx. Stars were visible across the entire disk, and the object looked decidedly like an open cluster. The 20-inch Clark refractor at Wesleyan University's Van Vlcck Observatory in Connecticut shows something more globular. Volume 2 of Sky Catalogue 2000.0 terms M71 “globular" without mention of any earlier controversy.

Many observers have commented on M71’s arrow-shaped appearance, but in photographs it is usually round. Its image in Hans Vehrenberg’s Atlas o) Sky Splendors is quite triangular. What do you see? Most observers iind t object uniformly illuminated, with no central core. Yet in the Messier All’^iun^ John Mallas drew the cluster with a pronounced bright edge, rather boomerang. I find no mention of such a feature in my observing notes, but ^_ebb Society Deep-Sky Observer's Handbook for open and globular clusters mentions a "nebulosity concentrated in the western part." What do you see? Remember to record the size and magnification of your telescope.

y\bout !6° south-southwest of M71 is the scattered group H 20. a very sparse bunching of about 15 stars in an area 7' across. They have a total magnitude of ■7 7 which makes the cluster brighter than M71. However. H 20 is much more difficult to pick out from the background sheen of the Milky Way. as compared with the tightly packed but fainter stars comprising M71. Here is a clear case of not being able to judge the conspicuousness of a cluster from its published magnitude alone. Experienced observers know not to draw a mental image of an object by its listing in a catalog, regardless of the amount of data given. So sparse is this cluster that without careful positioning of the telescope it is easy to overlook. Often, sweeping the area with a 4- or 6-inch telescope will fail to locate it. So inconspicuous is this object that it was not included in the NGC compilation.

To the west and a little north is a delicate splash of faint celestial fire known as NGC 6802. This small cluster is rather strongly elongated north-south. As a guide, there is a small grouping of stars to the west called Brocchi’s cluster, and NGC 6802 is at the east end of a 2°-long string of stars easily seen in any telescope.

The eastern end of Sagitta contains three very challenging planetary nebulae. Sky Catalogue 2000.0 lists NGC 6886 as 4" across and of photographic magnitude 12.2. In the early 1900s Heber D. Curtis made a composite drawing of this planetary based on photographs exposed from 10 seconds to an hour. In addition to calling the object 10th magnitude, he sketched it as 6" across. He also noted two projections that make the planetary look like a low-resolution photograph of Saturn. To date these projections have escaped my visual searches even with the 20-inch Clark. Perhaps someone can look for these features with one of the 29-inch Dobsonians now turning up across the United States.

The main disk of NGC 6886 is within the reach of a 4-inch telescope, but a word of warning is in order: Under poor seeing conditions the planetary may be difficult to distinguish from its surrounding stars. Todd Hansen of Potter Valley, California, used a 10-inch f/5.6 Newtonian to view the nebula. He notes it as “extremely small, bright, and slightly oval; at 180x sometimes like a fuzzy star; sometimes almost seems double.”

Another small planetary is NGC 6879. It is listed as 5" in diameter and photographic magnitude 13.0. Hansen could not make out the planetary’s disk. In •he Webb Society Handbook (Vol. 2) Pat Brennan reports that NGC 6879 appears stellar in an 8-inch reflector. He identified the planetary by using a small Pnsm at the eyepiece of his telescope. This simple accessory spreads the light of ^stars out into tiny spectra, while the planetary remains as a dot since its light is ^essentially from a single emission line at one wavelength.

Another planetary best detected with a prism is IC 4997. Its 2" disk is listed as P °tographic magnitude 11.6, and it has a central star perhaps two magnitudes ^nter. Hansen, probably on an especially good night, thought he could distin-^,sh the star at 360x but failed to do so on another night. English amateur Ed

Barker saw a slight indication of the planetary’s disk at 308x. At the time using an 8/z-inch reflector.

Although American amateurs have lagged behind their European counter parts in using a prism to locate small planetary nebulae, they have been quick use nebula filters. These dim the field stars while leaving the nebula’s brightn relatively unchanged. The filter can be flipped in and out between the eyepi^ and eye, making the nebula appear to blink compared to the stars.

Most of the many variable stars in Sagitta are faint, but S Sagittae is an inter esting object for observation with binoculars. It is of the Cepheid type, varvi between the visual magnitude limits 5.3 and 6.1 in an cight-day period.

Before leaving this rich area, double-star observers with small telescopes will want to view Zeta (Q Sagittae, an easy pair of 5th- and 9th-magnitude stars sep arated by 8". (The brighter component is a very close binary, beyond the reach of amateur instruments.) Theta (0) Sagittae is another easy double, magnitudes 6 and 9, separation 12".

Unraveling the Helix

One of Scotty's greatest and most respected traits was that he did not write to promote himself but to report on the progress of amateur astronomy. He made it his job to involve amateurs in that revolution; of course, he was often the one to get a fire going. Scotty was probably most satisfied when he received reports from amateurs who wanted to share their opinions on a particular subject of controversy. One great example of how Scotty promoted this sharing of knowledge can be found in his articles on the Helix Nebula in Aquarius. The Helix is a tough celestial nut to crack. Its pale hazy disk is often missed by amateurs who are accustomed to seeking much smaller objects. For advice, he would say, "Averted vision is needed, and the eyepiece field should be at least '/2⁰ in order to surround the nebula with some contrasting dark sky." As you will see here, readers of Deep-Sky Wonders had widely varied opinions on the object's visibility, and Scotty respected each and every one of them. His column was a forum for the amateur's voice to be heard.

10.7), lies in Aquarius about a third of the way from Upsilon (v) Aquarii to 47. It has a total magnitude of about 6, but its large apparent diameter — nearly half that of the Moon — spreads the light out and makes it a difficult object visually. Tire Herschels overlooked this nebula with their large reflectors. It is best to view this planetary with a rich-field telescope. With exceptional skies, an experienced eye will sometimes see traces of the nebular structure so vivi .

I recently saw the Helix Nebula with the 4-inch Clark refractor, and was ce tain that it was glimpsed in a 2-inch finder. Burnham notes in his ^^eeHandbook that it can be spied in binoculars. Years ago I suggested that rea

_ntj me their observations of the Helix Nebula, which I sometimes call the •‘Sunflower.” Over 200 letters were received, giving a good idea of its visibility in _niany instruments and at a variety of magnifications.

Harry Cochran of Brentwood,Texas, found the Helix difficult in a 12'/?-inch at (,7X though the view was better at 117x. On the other hand, to Leonard P. Farrar of Rialto, California, the planetary appeared much like its photograph. He used _a 10-inch mirror by Alika Herring in a mountain sky so clear that a flashlight beam was invisible.

Small telescopes in relatively poor skies seldom revealed color. Ted Komorowski told of a gray disk easily visible in his 8-inch f/7.5 at 56x. Yet Ray Lima of Jacksonville, Florida, readily saw blue-green in his telescope of the same aperture. When an object is near the visual threshold, color is not usually seen, only gray- To obtain maximum color perception, use the lowest magnification available.

The nebula's central hole was sighted by only a few observers, who included Michael Pleinis, Aberdeen, South Dakota (4- and 6-inch telescopes), and Mark

The Helix Nebula is the planetary nebula nearest to our Sun. At 15' in apparent diameter, it is also the largest.

Grunwald, Mishawaka, Indiana. Among others, Tom Burton of Santa Cruz, California, and N. Taylor in New Zealand could not see the central hole. Taylor ⁿ°ted that at higher powers NGC 7293 filled the field and details were lost.

The performance of instruments similar to Moonwatch Apogee telescopes ^varied. James H. McMahon, China Lake, California, glimpsed NGC 7293 at the J’rnit of visibility, after he had failed to see it a year before. Buddy Tempest, Columbus, Indiana, found it without using averted vision, while William O’Brian °f Gary, Indiana, easily saw the planetary at 16x and 25x, though it was invisible 7 x 50 binoculars.

The bulk of my correspondents indicated that thc Helix was more readily _Seein binoculars and finders than in telescopes. Yet some observers, such as Bj]| Perkins of South Boston, Virginia, had the opposite experience.

A few amateurs compared the Helix with familiar objects. For example Fr_eLossing of Ottawa, Canada, thought the binocular appearance of NGC 7293 \ similar to that of M33 in his 8-inch. Jan Finkelstein, Brooklyn, New York saw ^Sresemblance to M57 in his 2.4-inch refractor.

Atmospheric clarity obviously played a major role for seekers of the Helix Observers on mountains did much better than smog fighters, though the latte had easier viewing than one would have anticipated from Hans Vehrenberg’s statement in his Atlas of Deep-Sky Splendors: “Even on dark and extremely clear nights it is barely distinguishable as a very faint patch.”

Grunwald’s excellent results came after a cold front had just passed, making the sky so clear that M33 was visible to the unaided eye. Such favorable conditions should always prompt searches for the toughest deep-sky objects.

Most observers agreed that NGC 7293 was captivating. Edward Stockton of Lithia, Florida, recalled: “It was so faint that it seemed like a figment of the imagination, but its shape was unmistakable.”

In 1983 I again asked for observers' comments on the Helix Nebula, and a number of people replied.

Jim Meketa of Newton Center, Massachusetts, easily viewed the Helix with 7 x 35 binoculars. (Binocular vision often shows a fainter object than could be detected in a view with one eye alone. You can experiment by viewing a faint object with binoculars and covering one of the objectives. Chances are the object will disappear from the field.) Meketa’s binoculars showed the Helix as a “small ghostly doughnut,” but a 4'Z-inch finder on his 18-inch reflector showed some detail. The ring appeared unbroken, and there was an “unmistakable" tenuous glow inside it. There was no hint of the helical structure seen on photographs that give rise to the nebula’s popular name. Meketa believes that the Helix might be seen with the naked eye under excellent conditions.

In Georgia, David Riddle observed NGC 7293 with a wide range of instruments. It was “visible" in a 6 x 30 finder and “easy” with 8 x 40 binoculars. The central star was seen with a 6-inch f/4 Newtonian, and his best view came with an 8-inch f/6 reflector at 80x.

From Riverside, California, Stephan Karnes could not see the Helix with a 14-inch reflector until a nebula filter was added to the eyepiece to cut down the urban light pollution. Like Meketa. he noted faint nebulosity filling ⁽h^ecenter of the ring. Another Californian, Steve Gottlieb of El Cerrito, had trouble viewing the Helix with a 13-inch reflector at his home, while it was seen easily from high in the Sierras with a 6 x 30 finder and nebula filter. His con elusion is that thc visibility of the Helix is controlled more by sky conditions than telescope size.

One of the best reports came from Joanne Konst of Kenton, Ohio: ‘ N 7293, the Helix Nebula, is invisible without a UHC filter,” she writes. "But wit the filter 1 see a round glow about 15' across, and a dark center is obvious. Three _stars are seen against the nebulosity, but otherwise there is no detail."

A"Field Day" in the South

Occasionally a great celestial event forces masses of Northern Hemisphere observers to pack their gear and head south. Take, for instance, the 1986 return of Halley's Comet. Countless droves of amateurs armed with telescopes of various sizes descended upon the less populated regions of the south — the outback of Australia, the Alps _of New Zealand, or South America's barren Altiplano — simply to glimpse a part of astronomical history. But Scotty knew that these pilgrimages could yield even greater prizes. "The comet is going to have an effect on deep-sky observing," he predicted. "Flocks of amateurs are planning trips to the Southern Hemisphere, where many will have their first encounters with the glories of the southern sky ... I wouldn't be surprised if observers spend more time exploring the southern heavens than looking at the comet." And he was right. What he wanted to remind us, however, was that many celestial sights in the southern sky can be seen from northern locations. Here are a few of them that Scotty wanted readers to enjoy. Their declinations, he reminded us, are no farther south than that of the Scorpion's tail.

One of the great treasures of life is heaven’s starry vault on a clear night, when the familiar constellations blaze forth in mystical glory. It’s an extra treat if the sky is clear right down to the horizon and we can explore regions normally lost in thc haze.

In theory, everyone living south of the 45th parallel can see to the very bottom of Sagittarius. So they can try to hunt out four spiral galaxies in the constellation’s southeast corner; their presence was brought to my attention several years ago by New York amateur and author Phil Harrington. All arc plotted on Sky Atlas 2000.0, and Harrington remarks that they are “challenging finds for even the most accomplished deep-sky observer.”

Although they have eluded me from Connecticut, I saw them dimly with a 4-•nch rich-field reflector in the Arizona desert. Farther south at Puerto Escondito, Mexico, they were bright and easy in the same telescope. All are between 1' and 2' in diameter. The most obvious member of the group is 12th-magnitude NGC 6902, which shows some detail in a 10-inch aperture.

If these are too far south for your observing site, but you can see brilliant Fornalhaut in Piscis Austrinus, then try looking for another worthwhile quartet °f galaxies (Figure 10.8). NGC 7172 and the tightly bunched NGC 7173-74 and 2176 are visible in my 4-inch Clark refractor from here in Connecticut. They’re ^all about 12th magnitude, and plotted on Sky Atlas 2000.0. NGC 7172 is 2' across, but the other three are only half as large. John Herschel chanced upon them ^while sweeping the sky from the Southern Hemisphere. When he published a general catalog of deep-sky objects in the mid-1860s, over 90 percent of its 5,000-

Figure 10.8 if you can see Fomalhaut, you can find the galaxies NGC 7172, 7173, 7174, and 7176, which are clustered about 12° to the west.

plus objects were those discovered by him and his father William, and nearly 100 of the exceptions were from Messier’s famous list. Observers in the Americas had little to contribute.

After the U. S. Civil War, however, Americans went on an observatory-building binge. Funding for many installations came from state legislatures, since the astronomers provided time signals to their local areas. Almost every observatory from that era had a transit instrument for determining time. In return for this service the lawmakers funded a large telescope to keep the astronomers happy. When I was at the University of Wisconsin in the 1930s, Washburn Observatory still had the big brass fittings on the control board that routed time signals to commercial customers.

Most American observatories did not have special programs to search for deep-sky objects. Nevertheless, astronomers found new nebulae in the course of other work and published short lists of these accidentally discovered objects. By the time J. L. E. Dreyer compiled the NGC in 1888, the list had grown to nearly 8,000 objects.

About two dozen of these were discovered by Edward S. Holden with the 15'/’-inch reflector at Washburn Observatory in Wisconsin. One of them. NGC 6912, lies less than 1° west of Omicron (o) Capricorni. When Holden canu-across it on August 17,1881, he noted it as very faint. I still look at it when I get a chance — after all. there weren’t many deep-sky objects discovered in the state where I grew up.

Figure 10.9 The globular cluster M30 lies about 40,000 light-years away in the constellation Capricornus. It is best viewed with larger telescopes.

About 20° east-southeast of NGC 6912 is the globular cluster M30 (Figure 10.9), which Messier discovered in 1764. Although he saw it as a round nebula without stars, William Herschel resolved it into a “brilliant cluster” two decades later. About 8th magnitude and a bit over 10' in diameter, M30 is not one of the great globulars. Its bright center and easily resolved edges do, however, make it an interesting object for small telescopes. I find this sight rewarding in a 4-inch scope at 40x.

M30 can be a frustrating object for amateurs attempting a Messier marathon in March or April. Because of its position relative to that of the Sun, the cluster is almost impossible to find in either the evening or the morning sky, spoiling the chance to view all the Messier objects during a single night.

Sweeping northward from M30 into Aquarius brings us to several interesting objects. M72 is a globular both smaller and fainter than M30. In the 1930s I viewed it with the 13-inch reflector that belonged to the Milwaukee Astronomical Society and remember the edges of the cluster being well resolved.

Just east of M72 is a tiny group of four stars that Messier perceived as a dim glow and therefore included as entry 73 in his catalog. Some observers continue ^to debate whether this group belongs on the list with the French comet hunter’s °ther discoveries, but there is no doubt about its correct identity.

Only 2° northeast of M73 is a distinguished planetary nebula that Messier overlooked even though it was certainly within range of his telescopes. NGC ?0()9 is perhaps better known as the Saturn Nebula (Figure 10.10). The name

Figure 10.10 Nicknamed the Saturn Nebula because of its appearance in larger telescopes, NGC 7009 is one of the brightest planetary nebulae in the sky.

comes from Lord Rosse, who first saw two faint ansae extending from the central nebulosity, but the object itself was discovered by the elder Herschel. What is the smallest telescope that will show the planetary’s faint extensions? The nebula’s central star is about magnitude 11.5. It stands out like a beacon in my eye that had its lens removed in a cataract operation several years ago and is now sensitive to ultraviolet light.

Now we II have a field day in the sky below Fomalhaut, the brilliant lst-mag-nitude beacon in Piscis Austrinus. I like to think of this region as the pasture of Grus the Crane, the remarkably birdlike star group to Fomalhaut’s south. A number of galaxies here, while challenging objects from mid-northern latitudes because of their low altitude, are no farther down than the lowest stars in Scorpius’s tail.

IC 5271 is a spiral galaxy forming a neat little triangle with the 4th-magnitude stars Delta (8) and Gamma (y) Piscis Austrini. It is about 2' long and half as wide, large enough to be identified at 50x (though lOOx would be a better magnification with which to search for it). At magnitude 12.6 it can be seen in a 4-inch telescope when well above the horizon. Once, while in Mexico’s Sonora desert. I tracked it down with a 4-inch rich-field reflector at 40x. The sky was very good that night, and the naked-eye limit for stars was about magnitude 7.4. (It's always a good idea to note the naked-eye limit in your logbook, since I find this a much better indicator of sky transparency than the usual 1 -to-10 scale.)

A little over 2° south of IC 5271 is the similar-looking spiral galaxy IC 5269. The second Index Catalogue of Nebulae (which contains objects found between |g95 and 1907) lists it as very faint, pretty small, and round, to which I can reply, “No Y^es’^and somewhat.” IC 5269 is also the northernmost of five galaxies forming ^{a sma}" ^curv*ⁿg chain. It is easy to locate since it lies just west of the center _of a small triangle of naked-eye stars.

yiie two stars marking the base of this triangle are on the border of Grus. Almost on a line between them is IC 1459, an elliptical galaxy I estimate to be magnitude 10.0. Roughly '/2⁰ farther south is NGC 7418, discovered by John Herschel from Africa’s Cape of Good Hope. It’s a fat 3' in diameter and magnitude 11 -4- My 4-inch reflector gave a good view of it in the clear desert air.

The next galaxy in the chain is NGC 7421, which lies !6° almost due south of NGC 7418. It is about 12th magnitude. Another 14° to the southeast is IC 5273. Although about half a magnitude brighter than NGC 7418, it was missed by the observers whose discoveries were published in 1888 and is listed in the second Index Catalogue.

Star-hop to these galaxies by starting at Fomalhaut, moving to Delta (8) and Gamma (y) Piscis Austrini, and then to the small triangle of stars. This is a simple task — if the telescope and finder show the same sky orientation. On many commercial telescopes either the finder or the main instrument comes equipped with a star diagonal, which gives a mirror image of the sky. Trying to match this view with a star chart is like reading a newspaper in a mirror.

One solution is to use an Amici prism in place of the diagonal’s mirror or right-angle prism. Amici prisms combine the comfort of using a diagonal with a correct-reading image of the sky that can easily be matched to a chart. They are becoming increasingly scarce on the surplus market, but if you can find one I certainly recommend getting it.

A nice group of four galaxies forms a rough square straddling the -40° declination line on Sky Atlas 2000.0. While I don’t usually receive amateur reports of objects this far south, California observer Tokuo Nakamoto has seen at least two of them.

NGC 7410 is an obvious cigar-shaped galaxy at the northwest corner of the square. It is about 5' long and 2' wide. With the 4-inch reflector I estimated it as magnitude 10.0. Using a 6-inch f/8 reflector, Nakamoto found it brighter toward the center with a starlike nucleus. Much fainter is 12.7-magnitude NGC 7462 at ^[he square’s southeast comer. It is another thin spindle of light, about 3' long. Nakamoto noted that it has no apparent nucleus.

At the southwest corner, NGC 7424 is about 7' in diameter, nearly round, and 10-2 magnitude. At the northeast corner is NGC 7456, some 6' long, 2' wide, and magnitude 11.9. Can anyone confirm whether it has a stellar nucleus?

Before leaving this region of the sky, try for a tight group of four galaxies all ^Vlsible in the same telescope field 5° southeast of the square. Three of them are nice big spirals, all apparently barred, cavorting in a group like white beluga "'hales. The fourth is just to their west, off by itself. This is NGC 7552, listed as

visual magnitude 10.7 and 3' across.'rhe western galaxy of the triplet, NGC 75^ is cataloged as magnitude 10.6, but it seems to outshine NGC 7552 by even ino_rcthan the official 0.1-magnitude difference. NGC 7590, about a magnitude fainter is somewhat smaller than its neighbors. Of similar brightness to NGC 7590 ■ NGC 7599, though it is nearly as large as NGC 7582. I once marveled at these galaxies from the flanks of a smoking volcano in Guatemala.

Ast = Asterism; BN = Bright Nebulo; CGx = (luster of Goloxies; DN = Dork Nebulo; GC = Globulor Cluster; Gx = Goloxy; OC = Open Cluster; PN = Planelory Nebulo; ♦ = Stor; ♦ ♦ = Double/Mulliple Star; Var = Vorioble Slor__________ \

The Cassiopeia Milky Way

On November evenings the Milky Way arches over the pole like a phantom bridge. Here we are looking toward the outer regions of our galaxy where the star fields are less congested; a sweep of the telescope will reveal deep-sky objects peering out from the region's great swarms of stars. The W-shaped asterism of Cassiopeia appears to be a favorite proving ground for budding amateur astronomers scouting out deep-sky sights. Star-rich Cassiopeia does not disappoint, for it contains a fine assortment of open clusters scattered along the galactic equator, which passes through the constellation. "Curiously, amateurs seem to be relatively unfamiliar with most of these objects," Scotty wrote, "except the famous Double Cluster in nearby Perseus. Yet here are many open clusters that are relatively bright and easy to distinguish from the crowded star fields of the Milky Way. Cassiopeia, although usually not considered a hunting ground for clusters and not possessing any of the more interesting ones, is actually full of the smaller galactic clusters."

Novice observers have the universe before them to explore. To begin with, there are many dazzling and delightful objects which can be located almost effortlessly, such as the Orion Nebula, globular star cluster M13, and the Sagittarius star clouds. But what of the dimmer offerings, including many planetary nebulae and most of the NGC objects?

A fine harvest awaits the amateur who examines the Milky Way in Cassiopeia ^w’th a small telescope. Many readers have commented on the profusion of open clusters in the Cassiopeia Milky Way. Here we are looking toward the outer regions of our galaxy where the star fields are less congested and deep-sky objects ^are not lost among great swarms of stars. Still, some care is needed to recognize ^some of them against the starry background. On autumn evenings this region ^r|des high in the north, though it is awkwardly situated for finding objects with ^eciuatorially mounted refractors. Plate I of the Atlas of the Heavens shows 24 open dusters in the northern portion of Cassiopeia. An amateur who attempts to study •hem all will be kept busy for many nights.

^^e’ll start this month off with several open star clusters 1 have selected near

topeia. It is usually _Casier to pick out the_Seclusters with _arefractor work ⁱⁿ§ ^at f/15 than with the fa_stf/4 to f/6 _re. flectors that ^are popular today. For extended diffuse objects, faster optical systems give superior views, but when individual stars can be seen the high-power systems darken the sky background without diminishing the conspicuousness of the stars.

Queen Cassiopeia is usually portrayed seated in a chair, with the W as the constellation’s best-known part. Third-magnitude Delta (8) Cassiopeiae is the bottom point of the W’s eastern half, and just 2° to its southwest is 5th-magnitude Phi (<j>) Cassiopeiae. The open cluster NGC 457 is less than 10' west-northwest of the star and will be in the same low-power field of view. NGC 457 is a coarse group of distant suns which even shows well in a 2-inch aperture. This open cluster (Figure 11.1), 10' across, is a grand sight even in a 4-inch. The experienced French amateur G. Gauthier saw 50 stars here with a 6-inch reflector As the light-gathering power of the telescope increases, so does the number of stars that will be seen here, with a 20-inch revealing perhaps 100 stars appearing as bright pinpoints with dark sky between them. Many of this cluster’s stars are very faint, and even in the 20-inch refractor at Van Vleck Observatory in Middletown, Connecticut, scores of them dance in and out at the limit of vision.

Look about 40' northwest in the same field for NGC 436, a smaller cluster of fainter stars. (Be careful when observing the polar regions of the sky. for sky directions here will no longer match the corresponding compass points on the horizon.) When star-hopping from one location to another, it is important to know the actual field diameter of your eyepiece. Remembering how large the Moon (some /2⁰ in diameter) appears in your telescope will enable you to estimate the field with enough accuracy for this purpose. NGC 436 is a better target for larger telescopes. A 3-inch aperture will pick up about half a dozen stars here, while a 10-inch will reveal many more, and possibly the background glow of oth ers just below the limit of visibility.

since William H. Smyth, who in the mid-19th century called NGC 7789 a “mere condensed patch in a vast region of inexpressible splendor.” As examined in a 6-inch reflector by G. Gauthier, NGC 7789 is “a splendid swarm of about 200 stars of magnitude 10 to 12,” according to the observing manual Revue des constellations by Robert Sagot and Jean Texereau. Looking at this cluster, one may gain the impression of a knot of bright stars superimposed on a larger mass of faint points of light.

NGC 7789 is one of those rare objects that is impressive in any size instrument. With a 4-inch rich-field telescope the cluster appears as a soft glow nearly /i° across and speckled with tiny, often elusive, individual stars. The 12-inch f/17 Porter turret telescope at Stellafane picks up more than 100 stars. Through a 16-inch aperture the view is spectacular, and the whole field is scattered with diamond dust. And a 22-inch Dobsonian reflector in the clear skies of California gave a most impressive view with countless sparkling points filling an entire 60x field. I particularly like the draw-^lng of NGC 7789 made by Smyth, who observed with a 6-inch refractor. He mentions that the cluster has “rays of stars which give it a remote resemblance to a crab.” He imagined the creature’s head to be in the northwest with a close double star near where the eyes would be. Does anyone see this pattern today?

Kappa (k) Cassiopeiae, above the W’s center, is the 4th-magnitude star marking the front edge of the Queen’s chair. Just 22' to its north and in the same low-power field is NGC 146. It is a compact cluster containing about 50 stars within a 6' diameter of sky. However, the Milky Way background is quite rich here, and magnifi-eations between lOOx and 200x, especially with 10-inch and larger telescopes, will he necessary to appreciate the cluster fully.

Less than !6° west of NGC 146 is a very similar open cluster, NGC 133 group shines with a light equal to that of a 9th-magnitude star. This area of th_esky is historically interesting because the great supernova of 1572, Tycho’s star appeared some l'A⁰ northwest of these clusters. Attaining the brightness of Venus and remaining visible to the naked eye for 16 months, it was the most spectacular stellar outburst in the past 500 years. Although faint nebulosity believed to be associated with the explosion has been photographed with lar telescopes, it is well beyond the visual reach of amateur instruments.

NGC 225 lies 2° northwest of Gamma (y) Cassiopeiae, the famous irregular variable. The total light of the cluster matches a 7th-magnitude star. It was dis covered in 1784 by Caroline Herschel while comet hunting. William Herschel placed this cluster in his class VIII, which is reserved for coarsely scattered star clusters. W. H. Smyth described this as a loose cluster of about 30 9th- and 10th-magnitude stars. About 0.2° in diameter, it contains over a score of stars brighter than visual magnitude 13.1 prefer to view this object with my 4-inch Clark refractor, though it is quite evident in a 5-inch Moonwatch Apogee telescope.

NGC 129 is huge, having an apparent diameter as large as the full Moon. It lies midway between Beta and Gamma Cassiopeiae, and the 10 stars brighter than 10th magnitude in it are very scattered, so they do not define the cluster well. But on a very clear night, look with averted vision for a faint background glow caused by the dimmer stars. You'll need a 10-inch or larger instrument to resolve it, for it consists mainly of faint stars. As seen in a 10-inch reflector it is a triangle IT long. The brightest of its perhaps 50 stars is 9th magnitude

Cassiopeia contains the bright open cluster M52, which lies between Cassiopeia and Cepheus on the edge of the dark lane in the Milky Way that divides these two constellations. The early writers discuss the object under Cepheus, and there one should look for its description in either William Smyth's or Thomas W. Webb's catalogs. It arrived in Cassiopeia only in 1930 after the International Astronomical Union reorganized the official constellation boundaries.

M52 has a total magnitude of 7.2 and is visible in any finder. Recent studies indicate that this object is one of the richer and more compressed open clusters known. It is also relatively young, being some 20 million years old and comparable in age to the Pleiades. Unlike some open clusters, M52 shows increasing richness with larger-aperture telescopes. Smyth, viewing with a 6-inch instrument, was moved to call M52 an object of “singular beauty.”

Not large as galactic clusters go, it is 13' in diameter, but packed into that area are more than 150 stars of 11th magnitude and fainter. If it were not for its irregular outlines, M52 might well be mistaken for a globular cluster.

Only a little more than !4° southwest of M52 is the remarkable nebula NGC 7635. Although it is sometimes classed a planetary, it is hardly a typical member o this ill-defined group of objects. I first learned of this bubble of glowing gas in 19 when our Moonwatch station in Manhattan, Kansas, obtained a copy ^t'^ieSkalnate Pleso Atlas of the Heavens which plotted it. In the transparent skies of th^eGreat Plains my 10-inch reflector easily picked up the 3' nebulous disk surroun _ail 8th-magnitudc star. My experience was that the nebula was best seen at 150x.

Here in Connecticut I have never been able to find NGC 7635 with a 5-inch Apogee telescope at 20x, and my 4-inch Clark refractor revealed it only on a few _nights when the sky conditions were exceptional. Viewing from the Empire fountains of Arizona, Ron Morales saw the nebula as “two stars close together involved in nebulosity, roundish, faint, and large.” He was using an 8-inch at 5lx.

The Great Andromeda Galaxy

Amateur astronomers long await the November cold fronts that ferry in clean arctic air over much of the United States. Although these nights are crisp and cold, they offer us some of the best nebula observing of the whole year. During these evenings, M31 — the great Andromeda Galaxy — can be glimpsed with the naked eye regardless of the observer's location in the city or out in the country. Since it is more than two million light-years distant, M31 is one of the most remote objects that can be seen without optical aid. Naturally, because it is bright, so well known, and so easy to locate, M31 is frequently the first deep-sky object sighted by novice telescopic observers. "Initially, many see nothing more than a blob of light," Scotty said. "But with time and patience, beginners gain the ability to perceive greater detail. Seasoned observers find bright and dark lanes, star clouds, and a starlike nucleus to be prominent features of the Andromeda Galaxy." Interestingly, the full visual extent of this galaxy was lost to observers for nearly a century. The mystery has since been solved, and Scotty was present when the tables turned.

the days are mild and the nights are crisp and free of insect marauders. Ever since the summer solstice, the nights have grown longer and deep-sky viewing could begin earlier. The sweet perfume of red and golden foliage is in the air. The beau

November evenings, then, are a time to admire one of the most beautiful deep-sky sights of all — the Andromeda Galaxy, M31.

Well placed for observing near the meridian, M31 (Figure 11.3) lies a f_ewdegrees above Mirach, Beta (0) Andromedae, about 1° west of Nu Andromedae, and shines with a total light equivalent to a 4.5-magnitude star It seems the constellation boundaries of Andromeda were deliberately chosen so that nothing else would compete with thc Andromeda Galaxy for the deep-sk observer’s attention. And nothing can compare with it. M31 is relatively nearby being a member of the Local Group. It lies more than 2.2 million light-years distant and has an actual diameter of nearly 180,000 light-years, making it one of the largest galaxies known.

As early as the year 964 the Great Nebula in Andromeda, as M31 was once called, was described as a "little cloud” by the Persian astronomer al-SufT. This spiral galaxy can be seen with the naked eye even in a less than perfect sky Anything from an opera glass to the largest amateur telescope is suitable for viewing the galaxy. It is the chief glory of amateurs and a workhorse at public nights at observatories or star parties.

As with comets, M31 appears to have larger dimensions to the naked eye or through binoculars than when viewed with medium-sized telescopes, and the published values for its size vary widely. Most photographs of M31 show the spiral galaxy to be oval shaped, extending across some 2/2° of sky. This dimension is often given in catalogs. However, in 1847 with the 15-inch refractor at Harvard Observatory, George P. Bond traced the long axis to about 4°. His technique for observing the outer portions of the galaxy is still used today by amateurs searching for faint objects. Bond simply rocked the telescope back and forth, since the eye is better able to pick up a faint, low-contrast image when it is moving.

So strong is the desire to believe what astronomical photographs tell us that Bond’s observations have largely been overlooked even though they were mentioned in Webb’s Celestial Objects for Common Telescopes. That M31 is over 4° long was proven in the early 1930s, when Joel Stebbins of Washburn Observatory traced its extent with a photoelectric photometer. (I know, because I was a night assistant in the Washburn Observatory dome that evening!) This stimulated nty interest in reproducing the feat with the unaided eye, and I soon learned it was possible to do so on really excellent nights. Here is one of the cases where the eye can surpass photographic film. In 1953, the late French astronomer Robert Jonckheere, using 2-inch binoculars and taking extreme precautions, found the visible length to be 5° 10'. I can see the same with 15 x 75 binoculars. In fact, by moving the bright central region out of the field of view and by using averted vision, many people can do equally well with any low-power telescope. With my 5-inch Moonwatch Apogee telescope, I once seemed to reach 5°.

The apparent length of M31 is a sensitive measure of atmospheric trans parency. The slightest haze will drastically reduce what can be seen of the galaxy's faint extensions. I have never been able to see a greater dimension M31 with optical aid than I can with my naked eye. Indeed, Jonckheere liken the brightness of the galaxy's outer regions to that of the gegenschein. That faint glow is also seen best with the naked eye. A related project for the naked eye is to note how close thc edge of the Milky Way comes to M31. On really transparent nights I have seen thc luminous band come right up to M31 and then abruptly stop. On other nights a large separation appears between them.

Telescopically, M31 is often a disappointment. Few instruments can fit more than the galaxy’s central bulge in their field of view. If those in your group are familiar with photographs of M31, it would be best to tell them about the view through a telescope. Major features of the galaxy that are recorded by the camera are far more subtle in the eyepiece. Its spiral structure, first recognized in the mid-1800s by Ireland's Lord Rosse, probably cannot be seen in amateur instruments despite a few claims to the contrary. Another feature often lost in photographs is M31’s nucleus. The telescope shows a much brighter nucleus with the extensions quite faint. At low magnification the core of M31 appears as an even glow. But as the power is increased to several hundred or more, a tiny starlike nucleus becomes visible. High magnifications will help bring out this tiny, star-like part. With my 10-inch reflector in Kansas, this nucleus was very conspicuous in good seeing. Dark lanes in M31 can be identified even in small telescopes if the sky is dark enough.

A challenging project for the owner of a 10-inch or larger telescope is to locate the brighter globular clusters in M31. A description and finder chart for some of them appeared in the November 1979 issue of Sky & Telescope, page 490*. That idea came from Doug Welch of Ottawa, Canada. He had used his club’s 16-inch reflector to locate several of the brighter globulars, which had been selected from a list of nearly 250 suspect clusters in M31 compiled earlier this century by Edwin Hubble and Walter Baade (and cataloged with HB numbers).

After first mentioning these globulars in the November 1979 column, I received as much mail about them as about any other single topic. A few amateurs sighted some of the globulars easily, while others were just plain skeptical that such observations were possible.

Hank Feijth of Goutum, the Netherlands, held the brightest cluster, HB 12, steadily with his 6.1-inch reflector. He could also glimpse HB 64 and HB 254 with the same instrument. Feijth is an experienced variable-star observer with more than 30,000 magnitude estimates to his credit. On the other end of the experience scale was 15-year-old William Kinney of Whitefish, Montana. With a Celestron 8 he was able to view HB 12 as “fleeting with averted vision.” Unfortunately, space does not permit me to list all the amateurs who were able to see this cluster with only a 6-inch aperture. However, from the reports, it seems very likely that this is the minimum-size instrument for such an observation.

HB 254 was the second most observed globular, with several amateurs finding ¹¹ (with difficulty) in 8-inch telescopes. The most complete report on these clus-

™3l's brightest clusters are plotted on the Millennium Star Atlas, too. tcrs came from veteran variable-star observer Thomas W. Wilson of Hunting West Virginia. He found all 15 known clusters with a 12/?-inch f/5.1 homemade Newtonian. HB 90 was his most difficult observation. I find his results with an 8 inch f/5.6 homemade reflector even more impressive. With it he missed HB 9(j and only suspected four others, but the remaining 10 clusters were either seen _orclearly glimpsed.

Not all the interesting objects associated with the Andromeda Galaxy are as taxing of the observer’s ability as the globulars just mentioned. Familiar to today’s amateurs are the companion galaxies M32 and M110. In a small telescope, M32 is well separated south of the disk of M31 and may be mistaken for M110, also known as NGC 205. The latter, however, is much farther away (0.6° from the center of M31) to the northwest. Both of these satellite galaxies are about 9th magnitude. Curiously, its companion galaxy M32 was not noticed until 1749, although at 8th magnitude, it is obvious in very modest instruments. Ml 10. nearly as conspicuous, was discovered as late as 1773 by Charles Messier.

Two more companion galaxies, NGC 147 and 185, lie about 7° north of M31 and are often overlooked by observers. Visually, both these galaxies are several arc minutes in diameter and around 12th magnitude. NGC 147 is often listed in catalogs as being slightly larger and with a total light less than that of NGC 185. Thus, one would reasonably assume that NGC 147’s surface brightness would appear noticeably fainter than NGC 185’s. However, this is not the case. To me, they usually appear quite equal, and several entries in my notebook even cite NGC 147 as appearing a trace brighter. What is your opinion?

While some writers suggest that a 6-inch telescope is needed to ferret out these companion galaxies from the fringes of the Milky Way in Cassiopeia, I have seen both in a 4-inch instrument. Also, observers with large-aperture telescopes might want to check out a report by Tokuo Nakamoto. Using the 30-inch reflector at Stony Ridge Observatory in California, he suspected NGC 185 as being “granular” and thus on the verge of being resolved.

Sizing up the Fish

Pisces, a long, dim, and usually neglected region of sky, is nearly a ghost town of deep-sky wonders. "Few ever probe this area," Scotty wrote, "for here are found no planetaries, clusters, or nebulosities." Rather, he pointed out, "Pisces is all galaxies. In the region between right ascension 0^h and 2^h and declination 0° to +20°, we list 17 of these outposts of perception." One reason amateurs neglect Pisces is that its weak cast of galaxies must compete with the nearby presence of "magnificent M31," and the somewhat elusive but "marvelous M33." Only one of Pisces' galaxies is bright enough to be a Messier object — M74 — and it is the fabled thorn in the side of amateurs participating in Messier marathons. Therefore few observers even bother to turn their telescopes to it, or to Pisces. But, as Scotty explains here, there are many galaxies in the 12th- to 13th-magnitude range suitable for an 8-inch telescope.

galaxy from its catalog description. yet it is considered by many to be the most difficult object in Messier’s list.

Many famous observers have commented on the difficulty of viewing M74. Pierre Mechain, who discovered the object in September 1780, wrote: “This nebula contains no star; it is fairly large, very obscure, and extremely difficult to observe. One can make it out with more certainty in fine, frosty conditions!” His friend Charles Messier agreed that the object was obscure. Both Smyth and Webb omitted M74 from their observing guides, as have a chain of succeeding writers. Nevertheless, I have seen it in my 4-inch Clark refractor with the aperture stopped down to 2.8 inches. The delicate, sharply defined arms of this galaxy are very regular, which together with the broadside presentation, makes this a perfect object of its type. The arms cannot be seen in small telescopes.

John Herschel mistakenly classified M74 as a globular cluster, and this was not the only time it was misidentified. M74 has a rather bright, almost starlike nucleus, and when the famous Bonner Durchmusterung charts were compiled from observations made with a 3-inch refractor, the galaxy was included as the “star" BD+15°238.

One of the reasons amateurs have difficulty locating M74 is that its light is rather evenly distributed across the disk, thus yielding a low surface brightness. Your chances of picking it up are improved if you prepare to see a large, dim mass. M74 is easy to find, 1!4° east and 27' north of Eta (q) Piscium. As a guide ^to this spiral galaxy, there is an easily identified chain of stars about a degree to the northeast and visible in the same low-power field. If the observer sets Eta on the southern edge of a low-power field and lets the stars drift across, M74 will enter the field in a few minutes. This technique has a good deal to recommend it for the eye becomes much more sensitive by staring at a relatively blank sky for a while. Also, try viewing this galaxy with averted vision, which should give a fur ther gain of up to a stellar magnitude. Indeed, in most observing locations eye sensitivity is decreased by stray light, overall sky light, and reflections from the telescope tube. By shielding the head and the eyepiece with a black cloth, as a portrait photographer does, the observer will surely increase his ability to see faint objects, such as M74.

Paradoxically, M74 can sometimes be seen more readily in binoculars or a finder than in a 6-inch telescope. Its feeble contrast with the surrounding sky makes this a tricky object in any aperture. In the mid-1920s I caught a glimpse of M74 with a 1-inch 40x refractor. This was quite possibly due to the sensitivity of my young eyes since I was still in grade school at the time. At 60x, the 4-inch Clark stopped to 3 inches shows M74 as a galaxy. However, at 2 inches a quick glance reveals just the stellar appearance that gave rise to the mistake on the BD charts. A 10-inch shows that the central portion is brightest. No spiral arms can be seen, but it is obviously not a “nebulous star,” as some older accounts suggest. There is no question about it being a galaxy when viewed with a 20-inch aperture, but even then the spiral structure is not apparent.

NGC 524, a 1.5'-diameter elliptical object listed at 11th magnitude, is easier to see than M74. Because NGC 524 has roughly a twentieth the surface area of M74, but is only about 2'Z> times fainter in total light, its average surface brightness is some eight times greater. Once again, we find that the relative visibilities of objects should not be judged on the basis of catalog magnitudes alone.

NGC 128 is another interesting galaxy in Pisces. It is a tiny torpedo-shaped object about 2' long and a quarter as wide, and I estimate it to be magnitude 12.2. It can be seen in my 5-inch Apogee telescope at 20x.This telescope works well here because the star background does not overwhelm the deep-sky objects the way it does in places like the Milky Way in Aquila. NGC 128 has a challenging feature for observers: its central core is rectangular in appearance. Years ago in Kansas I could see this shape quite well with a 10-inch reflector, but it is beyond the grasp of the 4-inch Clark.

Smyth mentioned another difficult Pisces object, near the western end of the constellation: NGC 7541. It lies 1.4° north-northwest of the 4th-magnitude star Gamma (y) Piscium. This 3' long oval is similar in magnitude to NGC 128. As viewed with his 6-inch refractor, this galaxy appeared “so dim as to be only perceptible under settled gazing, and clock-work motion, when it faintly gleams among the telescopic stars in the field.” Yet my 5-inch Apogee telescope on a good night in Connecticut distinctly shows this 3' by T spindle, which I estimate as of visual magnitude 11.8.

Pisces also contains the interesting but elusive set of twin galaxies NGC 470 and NGC 474, which are separated by just 6'. While catalogs differ as to which _of them is brighter, I favor NGC 470 with a magnitude of 11.2. They were found quickly one night when I observed at my former home in Kansas, but there have been many nights here in Connecticut with my 4-inch Clark refractor when this instrument would not reach them. I wonder if they would be seen more in a sky _of better transparency. This galaxy’s light is concentrated within a 2' patch, and it is seen in the field of my refractor’s lOx eyepiece without any trouble.

Nearby is another pair of galaxies, this time more suitable for a 16-inch aperture. NGC 7619 and NGC 7626, separated by 7', are located on the border of Pisces and Pegasus. They are both about 1' in diameter and have cataloged magnitudes of around 12.7. There are over a dozen NGC objects within a 2° radius of this pair, and 1 suspect that many of them would be visible with a 10-inch telescope used in good skies.

As a challenge, look for NGC 7534, which is a part of a small chain of very faint galaxies a little more than 1° long running roughly east to west just below the celestial equator. A 16-inch telescope may be needed to show all of them. Work through this group carefully.

The Splendors of Sculptor

Although Northern Hemisphere observers cannot view the south celestial pole, they can see the South Galactic Pole and the splendors surrounding it in Sculptor. This dim constellation remains low in the southern sky for observers in mid-northern latitudes. However, its placement — as Scotty reminds us — is as good as the Milk Dipper of Sagittarius and the tail of Scorpius, which amateurs probe every summer night. "Sculptor contains many objects that would be the talk of every late-summer star party," he imparted, "if it were not for their relatively poor placement near the southern horizon." It's true. Without question, the deep-sky objects in Sculptor are some of the best in the entire sky, so they are well worth hunting down on those exceptional nights when cold fronts scrub the haze from the horizon and allow us to slant our telescope tubes ever deeper toward the south.

mateurs find it difficult to obtain visual descriptions of clusters and nebulae /Vwith large southern declinations. There is the extensive 1847 catalog of John Herschel, but the Southern Hemisphere seems never to have had a Smyth or a

Observers who have seen the whole sky often contend that some southern objects surpass the best the north can offer. When a clear, dark night is at hand, amateurs in mid-northern latitudes should attempt to view some of these southern wonders. Though low in the sky, their image quality is occasionally surprising. In November one may easily explore to the South Galactic Pole (declination -27°) in Sculptor.

Less than a degree from the South Galactic Pole lies NGC 288. This interesting globular cluster (Figure 11.5) is often overlooked by amateurs, though I readily find it whenever the sky is especially clear. One August, after a cold Canadian high had swept the air clean, binoculars were sufficient to distinguish NGC 288, which I make to be 12' in diameter and of , visual magnitude 7.0. Cata-' logs give its diameter as about 10', but

larger than M15 in Pegasus, but otherwise the two globulars appear about the same. In a pair of 5-inch 20x binoculars, it was possible to see individual stars around the edge of the cluster. And with a borrowed 12%-inch f/8 Newtonian reflector, the cluster could be resolved almost to its center. Only the regularity of the star pattern indicated that NGC 288 was a globular and not a compact open cluster. Furthermore, open clusters are concentrated along the Milky Way.

About 1.5° to the northwest is NGC 253, one of the largest galaxies in the southern sky (Figure 11.6). It is about 25' long (almost as long as the Moon is wide) and one-third as thick. At 7th magnitude it is a spectacular object for visual observers and astrophotographers alike. It is one of the 14 neb-_u|_ae and clusters discovered by Caroline Herschel in England during her sweeps for comets in the years 1782-83. Obser

ving from the Cape of Good Hope a half-century later, her nephew John Herschel described speculum-metal reflector: “Very, very bright and large; a superb object... 24' in length; breadth about 3'; position angle of long diameter 143.8°. Its light is someseem not to belong to it, there being many near.”

The galaxy was easily seen in Vermont with a 6-inch rich-field at about 20x. Long-exposure photographs reveal a complicated pattern of dust lanes and patches across its surface. Morales notes the galaxy’s internal mottling as “very impressive” seen with a 6-inch f/8 reflector. In the Wright telescope it was quite bright, and dark lanes were just visible. The sight reminded me a little of M31 in a 1.5-inch refractor in Connecticut.

There is always the possibility of discovering a supernova while viewing galaxies, but the chances are slim. One difficulty is that amateur telescopes usually reveal only the bright inner core of a galaxy, and an outlying supernova will look like any other field star. This was my experience in 1972 when viewing the bright supernova that erupted in NGC 5253 in Centaurus. Of course, if an unfamiliar star is seen superimposed on the galaxy’s image, it is a much more likely supernova candidate.

Southward from the galactic pole and near the 5th-magnitude star Eta (r|) Sculptoris is NGC 134. Though llth-magnitude and only 5'x l'in size, this object was held steadily in my 4-inch Clark refractor. The view was not as good as one I had from Louisiana in 1943. But despite its low altitude NGC 134 is no more difficult than NGC 6207, a well-known spiral galaxy near M13.

If you have an unobstructed horizon, try adding two even more southerly galaxies to your Sculptor list. NGC 300 is another large spiral (Figure 11.7) seen ‘ace-on that spans 20' by 10'. Steve Coe of Arizona found it to be very much like the well-known M33 in Triangulum. With a 13-inch telescope he can just discern ^a dim S-shaped structure. To my eye its total light is equivalent to an 8.5-magni-tude star, but since it is spread out over so large an area, the surface brightness is low. Care is needed to locate this object, but it can be seen in a 5-inch Moonwatch Apogee telescope. With a 10-inch reflector in Kansas, I found this galaxy to be fascinating, with abundant detail that challenges anyone who attempts to make a drawing.

While scanning the Sculptor Croup, look for the large spiral galaxy NGC 55. It lies within 15° of the South Galactic Pole.

Some deep-sky objects offer beautiful, breathtaking visual experiences. NGC 55 is one such object (Figure 11.8). It is the largest galaxy in the nearby Sculptor Group and by itself is one of the giants of the southern sky. In fact, these objects form the nearest cluster to our Local Group, being only some 13 million light-years away. From observations made in Mexico, where NGC 55 rises much higher than as seen from most of the United States, I estimated its total magnitude to be 7.1. When 1 first saw NGC 55 in binoculars from Chiapas, I was surprised that such low power would reveal this galaxy so clearly.

Most amateur telescopes can trace NGC 55’s slender, spindle-shaped form across 20' of sky. Long-exposure photographs record more than a Z° length, and densitometer measurements of these negatives reveal a disk that approaches 1° long. This makes it an excellent candidate for viewing in a black sky with binoculars. Remember that the Andromeda Galaxy, M31, can be visually traced out to almost 5° with binoculars, whereas photographs usually stop at 2%°. Has anyone tried viewing NGC 55 with a light pollution filter? The results might be surprising-

Houston, Texas, amateur Barbara Wilson, whose prowess as a deep-sky observer is legendary, sent some of her notes regarding NGC 55. “August 9,1986. 3 a.nt., seeing good, very transparent night at Columbus, Texas. Using the 13.L inch [at 115x], NGC 55 appears very large, extremely elongated, very mottled, slightly tilted, very bright, however east end fades rapidly.”

A year later from the same site she viewed NGC 55 again, this time with a j7.5-inch telescope: “A long streak narrower at one end with mottling in the central region visible at 97x. It fills the 0.52° field of a 21-mm eyepiece. Incredible! Spiral almost edge-on. extremely bright, dimmer [east] end seen easily as it lades into the sky background, it is wider, but of lower brightness, than west end."

Can the famous Sculptor Dwarf Galaxy be detected visually? I still remember the excitement in 1938 when Harvard astronomers announced a hitherto unknown stellar system at only about an eighth the distance of the great Andromeda Galaxy, M31.

Although it has a total magnitude of about 8 and is more than a degree in diameter, the Sculptor system is most elusive because of its very low surface brightness. It consists of a loose swarm of thousands of stars of magnitude 18 and fainter.The discovery was made on a photograph taken with a 24-inch telescope, with a long enough exposure for the individual stars to show.

But the Sculptor system was also detected on a plate exposed for 23.3 hours with a 1-inch f/13 patrol camera, which revealed it as a very dim, unresolved smudge. Harvard’s medium-sized photographic instruments recorded nothing.

The best hope of seeing the Sculptor Dwarf Galaxy (Figure 11.9) is probably with a small, low-power, wide-field telescope or big binoculars, on an exceptionally clear night. Success may require considerable observing skill and first-class vision. Amateurs with fast telephoto lenses of medium focal length (300- to 500-mm) can record this system.

Figure 11.9 The loosely organized Sculptor Dwarf Galaxy measures a mere 8,000 light-years in diameter and has a mass of only about 2 million Suns.

On November evenings Sculptor is near the meridian about the time evening twilight ends. The elusive galaxy is about 4° south of 4th-magnitude Alpha («) Sculptoris. When I first presented readers with a Sculptor challenge in 1971, no one answered. This wasn’t surprising since the galaxy consists of very dim stars spread over a very large area. Some people have compared the galaxy to a huge globular cluster with 99 percent of the stars removed. Recently, however, I received a letter from Steve Coe in Arizona. From a dark-sky site he had searched without success for the Sculptor system with a 17/z-inch reflector. He then tried a 4/2-inch f/4 reflector at 16x. After carefully dark-adapting his eyes and covering his head with a dark cloth to prevent stray light from interfering with the view, he swept the sky again There it was, a blob of light without any detail, but visible nonetheless. Why don't you give it a try?

The Naked-Eye Milky Way

It's ironic, but we amateur astronomers often miss the forest for the trees. How many nights have we spent squinting behind an eyepiece just to glimpse the dim and fuzzy glows of distant galaxies? How many nights have we tried to seek out hyperfine details — a dust lane, a stellar nucleus, an H II region, a knot — within these ghostly extragalactic bodies? And while we strain our eyes, the most detailed galaxy of all goes virtually unnoticed. It's called the Milky Way, and we hardly know what it looks like to the naked eye. In the November 1990 Deep-Sky Wonders column, Scotty awakened himself — and us — to that obvious fact. While attending the Texas Star Party one spring, he sat in a chair under the stars and rediscovered the Milky Way. "1 just observed," he said, "with that marvelous and often ignored optical instrument, the human eye."

One of the best observing experiences of my life came unexpectedly in May 1990 at the Texas Star Party (TSP). From 11 p.m. to 3 a.m. I simply sat in a chair and watched the Milky Way.

Held in the shadow of Mount Locke, home of McDonald Observatory, the TSP usually has the best observing conditions of the big three annual conventions in the United States — the other two being the Riverside Telescope Makers Conference in California and Stellafanc in Vermont. The TSP has virtually no light pollution, and this year the air was very dry and transparent. The stars actually looked like sharp points.

For my Milky Way survey I used no telescope, though several dozen were close at hand and probably mine for the asking. The little 8 x 15 binoculars never left my shirt pocket, either. Even my Lumicon nebula filters, which I’m never without these days, stayed safely in a box. I just observed with that marvelous and often ignored optical instrument, the human eye.

Furthermore, I just looked at the summer Milky Way (Figure 11.10a and b)-¹¹⁰¹searching for anything in particular but alert for anything unusual. I wanted

The sparkling winter Milky Way, accompanied by the constellation Orion and the bright star Sirius. purely naked-eye impressions, not photographic, not photoelectric, only what I could see.

It was a wonderful experience.The turbulent star clouds appeared so crisp and well-defined. The most luminous part of the strip, running from Cygnus at the zenith to below Scorpius on the mountainous southern horizon, was remarkably narrow. I was suddenly struck by how thin the disk of our galaxy really is. and how closely packed the stars are within it. I was also surprised by the band’s straightness. The concept of thc Milky Way as an ill-defined, irregular, pythonlike stellar monster had given way to thc image of a slender shaft following a purposeful straight line across the sky. It was not a sight you glean from looking at star maps. I now have a better feel for the legends that call thc Milky Way the backbone of the sky.

I was most surprised by how isolated Antares and the globular cluster M4 are from the galactic disk. Except for a faint haze, the sky east of Antares is vacant — rather like the sky west of M4. which all star charts place outside the edge of the Milky Way. Now, you can reason that the void east of Antares is due to dark dust clouds, and this is fine scientifically. But the eye is not aware of what is happening here, and thus Antares appears outside the Milky Way.

In getting this column together I searched through my library for amateur oriented books that devote solid space to the visual Milky Way. I found many brief accounts of localized areas such as the star clouds of Cygnus and Sagittarius, but little on the naked-eye Milky Way as a whole. Then I turned to Garrett P. Serviss’s classic Astronomy with the Naked Eye. It contains an entire chapter on the subject. Serviss relates a folk tale he picked up from Lafcadio Hearn, a turn-oi the-century writer who used words to paint full-color pictures in three dimensions.

According to Hearn, several Eastern cultures had variations on a tale of a herdsman falling in love with a weaver named Orihimd. In anger, Orihimd’s father banishes the lovers to thc sky where they become the constellations Aquila and Lyra. Once a year they are allowed to meet if they can cross the Celestial River of the Milky Way. Serviss concludes his chapter by quoting Hearn:

In the silence of transparent nights, before the rising of the moon, the charm of the ancient tale sometimes descends upon me out of the scintillant sky, to make me forget the monstrous facts of science and the stupendous horror of Space. Then I no longer behold the Milky Way as that awful Ring of the Cosmos ... but as the very Amanogawa itself — the River Celestial. I see the thrill of its shining stream, the mists that hover along its verge, and the water-grasses that bend in the winds of autumn. White Orihime I see at her starry loom, and the Ox that grazes on the farther shore — and I know that the falling dew is the spray of the Herdsman’s oar.

Although the Milky Way has forever been so conspicuous in the night sky that it is woven into folk tales everywhere around the world, it is slowly attaining the status of a “test object” because of the ever-spreading threat of light pollution.

Ast = Asterism; BN = Bright Nebulo; CGx = Cluster of Goloxies; DN = Dork Nebulo; GC = Globular Cluster; Gx - Goloxy; OC = Open Cluster; PN = Monetary Nebulo; * = Star; ** = Double/Mulliple Sfor; Vor = Vorioble Sfor

Ast = Asterism; BN = Bright Nebulo; CGx = Cluster of Galaxies; DN = Dork Nebulo; GC = Globular Cluster; Gx = Galaxy; OC = Open Cluster; PN = Plonefory Nebulo; * = Slor; * » = Double/Mulliple Star; Vor = Variable Star

DECEMBER

The Challenge of the Seven Sisters

On December evenings the most remarkable star cluster in the heavens, the Pleiades (often called the Seven Sisters), rises to prominence. "Even on the coldest winter nights, when time spent at the telescope is better measured in minutes than hours, it would be a very un-amateur act not to look in on the Pleiades," Scotty quipped. As far as he was concerned, the Pleiades were worth looking at every clear night, and for good reason. Seasoned amateur astronomers know that the state of Earth's atmosphere can change from night to night or minute to minute. And the clarity of our atmosphere makes the difference in seeing not only the fainter members of the star cluster with the naked eye — the exact number of which has long been disputed in amateur circles — but also any telescopic traces of the delicate nebulosity that swaddles the entire cluster, like jewels in a bed of vapors. "On an ordinary night," Scotty pointed out, "there are usually a few wisps of nebulosity seen around the Pleiad Merope. But on really exceptional nights (or more likely, half-hours), the glow swells out to encompass the entire cluster in a big cocoon."

December brings winter, and with it many cold but often clear nights. On such evenings, when the stars sparkle like diamonds, there is no sight as spectacular as M45, the Pleiades (Figure 12.1). Currently, this open star cluster rides high in the eastern sky at the end of astronomical twilight. It is delightful in any instrument, from the naked eye to the largest amateur telescope, although I find large binoculars give the most impressive view. Almost every culture, past and present, mentions in its folklore the dazzling stars of this nearby cluster. They have enhanced the imaginations of gifted poet and commoner alike as far as we ^can remember. They are the starry seven of Keats, the fireflies tangled in a silver hraid of Tennyson, the fire god’s flame of the old Hindus, and the ceremonial ^razor of old Japan. No other celestial configuration appears so often on the pages °f the poet.

Astronomers have studied the Pleiades in great detail. The 19th-century author Agnes Clerke wrote that the cluster is “the meeting-place in the sky of mythology and science.” Our present knowledge of stellar evolution suggests that the

Pleiades are only 20 million years old. Thus, mammals were well established on Earth when the Pleiades’ light first fell upon it. I am always taken by the fact the dinosaurs never saw the Pleiades, for even as the last of those beasts roamed the land 65 million years ago, it would be another 45 million years before the Pleiades would begin to shine.

M45 is a little less than 2° in diameter — too large for the Moon to occult all of its stars at once. Partial occultations of the cluster recur in an 18.6-year cycle, as the Moon’s nodes regress along its orbit.

Have you ever tried to count the Pleiades with the naked eye? Experiments show that light entering the eye from the side reduces sensitivity and contrast. Thus, I made a cardboard tube about a foot long and a foot in diameter that I painted flat black on the inside. Unfortunately it didn’t help me see more stars. In fact, so much light bounced off the sides of the tube that I saw fewer stars with it than without it. Do not consult a chart while you are trying to count Pleiads. Instead, make a careful drawing of what you see and compare it with a chart later.

Depending on light pollution and sky conditions, most persons can see between four and six naked-eye Pleiads. Traditionally, the average eye can sec six stars here, the exceptional eye seven, and 10 bear names or Flamsteed numbers. However, during the 1800s the noted British amateurs Richard Carrington and William Denning both counted 14 stars. The late dean of visual observers. Leslie peltier. told me he could always see 12 to 14 stars there on any good moonless _nj_eht. Perhaps because it has been repeated so many times that the number of naked-eye Pleiads is six or seven, too many observers quit counting before really reaching their limit. Many observers can reach magnitude 7.5 with the naked eye. Were it not for the bright Pleiads, these observers should be able to count upward _of 30 stars in the group.

In 1935 at Tucson, Arizona, I was able to make out 14 Pleiads with ease, despite _my “class 2 eyes,” and as many as 18 under exceptional skies. Forty years later from the same location, deteriorating observing conditions had reduced this number to five. The reason was apparent even before the sky darkened, for heavy clouds of smog from copper smelters had settled into the natural bowl where Tucson is located. In the sooty skies of our populated areas, it is now not uncommon that no stars can be distinguished; the eye sees just a shimmering patch. So the number of Pleiades stars visible is really an index of the transparency of the atmosphere, and the cluster does not make a valid eyesight test. If you look at this cluster only infrequently, one glance will not tell you much about the sky conditions. But with practice you’ll know by the cluster’s appearance whether the night is a particularly good one.

The stars of the Pleiades were born so recently (by astronomical standards) that some of the lingering dust and gas of their birth still surrounds the stars*, especially Merope (Figure 12.2). As early as 1859, the German astronomer Wilhelm Tempel observed this nebulosity surrounding the Pleiad Merope with a 4-inch refractor in Italy. Others using larger instruments failed to see it, and some doubted its existence. Photography, however, proved that the nebulosity is real, and the quest was on to see as much of it as possible visually.

From Tucson my 4-inch showed it readily. In Connecticut, a 10-inch reflector failed, but in Vermont a 5-inch Moonwatch Apogee telescope succeeded. At the August convention of the Astronomical League in Tennessee, I was surprised to find several observers who had seen the Merope Nebula more than once. It was readily visible in a 6-inch reflector made by Fred Lossing of Ottawa. Once its position southwest of the star Merope was pointed out, others saw the dim glow too. In the 16-inch, the nebula seemed much more obvious, and averted vision was not required.

Recent research suggests that the Pleiades may simply be passing through unrelated nebulosity.

In addition to the well-known glowing “thumbprint” of material south of Merope, the cluster is surrounded by a faint cloud of nebulosity. As with seeing naked-eye Pleiads, its visibility is more a test of atmospheric transparency than observer skill. The 19th-century comet observer Heinrich d’Arrest wrote of the Pleiades, “Here are nebulae, invisible or barely seen in great telescopes, which can easily be seen in finders.” Most amateurs are content to glimpse the wisp near Alcyone. But I have seen nebulosity curdling and weaving well beyond the brightest stars of the cluster. My 6-inch f/4 Cave mirror in Connecticut occasionally gives fine views of this.

With low-power telescopes and the excellent dark skies of Arizona, California, and Kansas, I have easily seen the nebulosity as a bright cotton ball encompassing the cluster. But even the slightest traces of dew on the optics will give the same impression, and I constantly check for this by looking back at the nearby Hyades cluster. Today observers have little trouble seeing the entire Pleiades cluster immersed in nebulosity when observing conditions are right.

A number of amateurs claim to have observed this nebulosity with the naked eye, and I tend to believe them. You might investigate this by carefully comparing the appearances of the Pleiades and the Hyades, to see if there is any differ' ence in what might first be perceived as sky background brightness.

Another feature of the Pleiades is mentioned in a letter by skilled variablestar observer Stephen Knight of East Waterford, Maine. He writes, “There is ^adimly visible dark ring that encircles the outer boundary of the diffuse nebula. H is irregular in width and darkness. One of the darker and more easily seen parts is just north of Asterope and between it and 18 Tauri. I first spotted the dark ring with my 6-inch reflector and low power, and I followed it all the way around the bright nebulosity. It appears as an area with an absence of faint background stars _or glow from the outskirts of the nearby Milky Way. The most difficult part to see j_s south of Merope and Electra.” Later Knight reported seeing weakly luminous material outside the ring.

At the turn of the century Edward Emerson Barnard photographed this bright outer nebulosity, so its reality is not questioned. But how many people can see it visually? It is certainly more difficult than the California Nebula, and probably on a par with the Sculptor system. I suspect that this will be a test object that will be around for a while.

Taurus: The Observer's Paradise

When December rolled around, Scotty said he often first turned his attention to the famous Double Cluster in Perseus, high overhead. Then, looking to the southeast, he paused for a long look at the brilliant V of the Hyades cluster — the face of Taurus the Bull. 'The 7° field of view in standard 7 x 50 binoculars," he said, "will hold the cluster comfortably along with 1 st-magnitude rose-tinted Aldebaran." The area of sky containing the head and horns of Taurus is a veritable playground for amateurs using binoculars and small, rich-field telescopes. Especially noteworthy are its bright open clusters, and of course, the famous supernova remnant of A.D. 1054, more commonly known as M1 or the Crab Nebula. Taurus also contains another object of historical significance: the planetary nebula NGC 1514. As Scotty explains here, Herschel's discovery of this object "marked a turning point in the thinking of this great astronomer."

The constellation Taurus is well placed in the evening sky this month. Situated along the western edge of the Milky Way, Taurus might be expected to contain the swarms of open star clusters that pepper the constellations of Cassiopeia, Perseus, and Auriga. But this is not the case, and observing guides rarely list more than half a dozen clusters in Taurus. Furthermore, despite being the 17th-largest constellation, it contains no galaxies and only one planetary nebula within the reach of amateur telescopes.

Yet,Taurus is still an observer’s paradise. Objects within its borders range from •he magnificent naked-eye Pleiades and Hyades star clusters to a giant 3° bubble °f glowing gas similar to the Veil Nebula in Cygnus (called S147).The Hyades star cluster is rather close to us, and its stars appear spread over quite a large area. Unlike the Pleiades, there is no nebulosity associated with the group. In fact, whenever I think I’ve sighted the wispy glow between the Pleiades, I quickly turn ^to the Hyades to check for a glow there, too. If I see any, then I know to blame a slight dewing of the optics, even if their surfaces look clear.

Another cluster is NGC 1807.1 estimate it to be about 15' in diameter with a total magnitude a little brighter than 8. However, the 30 or so stars that a 10-inch telescope shows here are so scattered that thc total magnitude has little bearing on thc cluster’s actual visibility. NGC 1807 is seen quite well in my 4-inch Clark refractor, and the view in 60-mm binoculars is also pleasing.

Just 0.4° to the northeast, and in the same field of a low-power eyepiece i« NGC 1817. This open cluster is about 20' across, and some astronomers suspect it may be physically associated with NGC 1807. English observer Kenneth (i|y_nJones reports that, with an 8-inch reflector at 40x, NGC 1817 looks like two clusters in contact with each other. While a 10-inch telescope may reveal 20 stars here, the number may more than double in a 12-inch. Amateurs with access to large-aperture telescopes should record their counts.

The open cluster NGC 1746 presents a classic problem for visual observers —-what is its apparent diameter? Modern catalogs often list its size as 45'. However estimates range from 25' to 1°, with the larger telescopes usually givim the smaller values.

Figure 12.3 Look for the planetary nebula NGC 1514 near the Perseus/Taurus border. Its central star easily outshines the surrounding nebula.

NGC 1514 is the sole planetary nebula that amateurs can find easily in Taurus (Figure 12.3). It was discovered by William Herschel in 1790, and it marked a turning point in the thinking of this great astronomer. Until then it was widely accepted that nebulae were just clusters of stars either too faint or too distant to be resolved. But Herschel saw NGC 1514 differently:

A most singular phenomenon! A star of about Sth magnitude with a faint luminous atmosphere, of circular form, and about 3 minutes in diameter The star is in the centre, and the atmosphere is so faint and delicate and equal throughout that there can be no surmise of its consisting of stars; nor can there be a doubt of the evident connection between the atmosphere and the star.

Thus, for the first time it occurred to Herschel that there existed a “shining fluid of a nature totally unknown to us." By the mid-19th century, spectroscopy proved beyond a doubt that glowing nebular gas was an astronomical reality, but when you look at NGC 1514 bear in mind that the concept began here.

To me NGC 1514 appears more like a nebulous star, for, unlike other planetaries where the central star is often a challenge, NGC 1514’s luminary almost dominates the view. Years ago in Kansas I saw the star (listed as 9th magnitude) in a 4-inch telescope stopped down to 2 inches. The surrounding nebula is slightly oval and about 2' in diameter. Some observers consider this object difficult for an 8-inch telescope.

NGC 1555, Hind’s Variable Nebula, deserves more attention from amateurs. It is associated with the variable star T Tauri, which fluctuates irregularly between about magnitude 9 and 13. There is no clear relationship between the star’s brightness and that of the nebula. Both objects were discovered in 1852 with a 7-inch refractor by the Englishman John Russell Hind.

He reported NGC 1555 to be 4" southwest of the star. By 1868 the nebula had faded from view. It was rediscovered by Barnard and Sherburne W. Burnham in 1890 with the 36-inch refractor at Lick Observatory. Five years later the nebula had again vanished, but it was recovered photographically in 1899 and has been followed ever since.

NGC 1555 has brightened significantly since the early ’30s. Not only has its brightness changed, but apparently so have its shape and position. Currently it is due west of T Tauri, and photographs suggest that NGC 1555 is part of a shell of material surrounding the star. My last observation of it was in 1977 with the 4-inch Clark at 150x. At lower magnifications it could have been easily overlooked.

It’s a short hop from the heart of the Hyades to Ml, the Crab Nebula (Figure 12,4). During the 20th century Ml was discovered to be a source of strong radio emission. In the 1950s, Cliff Simpson and I operated several radio telescopes at Manhattan, Kansas. Although they were built from odds and ends, they were carefully assembled and quite sensitive. The signal from Ml was among the half-dozen strongest on our list. Ml has been carefully studied by radio and X-ray astronomers. It is known to be the remains of a supernova which exploded in A.D. 1054, and the pulsar at its center is suspected to be a rotating neutron star. The supernova was visible even in the daytime, but it wasn’t until 1731 that the nebula was first seen, by the English amateur astronomer John Bevis. Messier independently discovered it 27 years later in 1758. Traditionally, it was this object that induced Messier to compile his famous catalog of nebulae and clusters, so these deep-sky features would not again be mistaken for comets in his small telescopes; it was also in the search region for the 1835 return of Halley's Comet.

In December 1852, the English telescope maker and observer William Lassell used a 24-inch speculum-metal reflector to view Ml from Malta. He noted, "With 160x it is a very bright nebula, with two or three stars in it, but with 565* . . . long filaments run out from all sides and there seems to be a number of minute and faint stars scattered over it.” On January 6th of the following year Lassell reobserved the Crab with 565x: “The brightest parts are about 2' j_nlength, while the outlying claws are only just circumscribed by the edge of the field of 6' in diameter.”

The Crab can be seen in 2-inch finders. Small telescopes reveal only a shape-less 8th-magnitude blur variously sketched as oval, rectangular, or more often something in between. The Crab Nebula usually shows in small telescopes as a featureless gray ghost. My 4-inch Clark refractor has revealed hints of the nebula's ragged edge that appears so prominently in photographs. These edge serrations are usually apparent in a 12-inch telescope and easy in a 17-inch. Increased magnification does not seem to change the appearance much. Telescopes of 12-inch aperture and larger often reveal delicate filamentary structure in the nebula.

My impression is that large amateur reflectors do not show much more of the Crab Nebula than a 6-inch does, though of course they show it better. Amateurs with access to a 16-inch or larger telescope, perhaps a club telescope, can perform some interesting experiments on how the appearance of Ml varies with different magnifications and telescope f/ratios. The latter can be changed by

making aperture masks of varying diameters. Mike Mattei of Littleton, Massachusetts, has suggested using a nebula filter in the “flicker” I mode. By rapid-I ly moving it in I and out of the * space between the eyepiece and your eye, it is easy to note the effect of the filter. I tried this technique using a 15 x 65 monocular at my home in East Haddam. The

Crab was easily detected with the flicker method, but I was unable to hold the nebula steadily when viewing either without the filter or with it fixed in place.

Light pollution does affect the visibility of Ml, and many amateurs, especially from the East Coast, report that they have despaired of seeing this nebula, even though it is 9th magnitude and about 4' in diameter. My mail is divided on how well nebula filters work on this object. What do you find?

Targeting the Cetus Seyfert

The key to successful galaxy hunting is being able to read and interpret a star chart. Of course, such a skill is indispensable for finding virtually all deep-sky objects. There is no escaping that fundamental necessity. Fortunately, the sky has its celestial coincidences — such as a bright galaxy lying near a naked-eye star — which benefits beginners looking for a good place to practice their hunting skills. "The job of locating faint deep-sky objects is always made easier if there are nearby finder stars," Scotty once instructed his readers. The constellation Cetus is home to one of these celestial coincidences, for near the 4th-magnitude star Delta Ceti lies the bright Messier galaxy, M77, which is also one of the sky's weirdest. As Scotty explains, the galaxy not only perplexed early telescopic observers but also modern-day astronomers.

A s I gather my thoughts and begin writing this column, it is a musty, rain-soaked

/v August here in Connecticut. But I look at “December” typed at the top of the page and think to myself, “Ah, in December the rains will be long gone and the cold arctic air overhead will let the Milky Way erupt, trailing clouds of glory across the heavens. Then, with the help of a hefty snow shovel, those of us in the Northeast may occasionally dig out our telescopes enough to do some useful work.”

I can only hope that this will be the case, for 1990 has been a particularly poor year for clear skies in New England. Then again, treasured in my old-letter file is a 1930s missive from Leon Campbell, the first recorder for the American Association of Variable Star Observers. In it he complains that during the previous month the weather was so bad that the AAVSO received not a single observation from Massachusetts or Connecticut. So if the weather confounds your observing program, the remedy is simple: live long.

December is a fine month for viewing Cetus, the Whale. This constellation, which swims mostly just under the celestial equator, is presently near the meridian during evening hours. If you work with 8- to 12-inch telescopes, there are many fascinating galaxies in Cetus worth hunting down. In this part of the heavens our gaze is away from the plane of the Milky Way. Indeed, just over the Cetus border in Sculptor is the South Galactic Pole. Here we are looking into the depths of the universe, beyond our own galaxy’s veil.

Those who use 17-inch and larger telescopes will no doubt be able to find many more galaxies than shown on charts like Tirion’s Sky Atlas 2000.0. While many of them can be found in the New General Catalogue of Galaxies and Clusters of Stars (NGC), others will be listed only in specialized catalogs. Correctly identifying these galaxies can be a real challenge, even for the amateur who has a good reference library.

Learning to use a good atlas, preferably one showing 9th-magnitude stars, is another important project. Frequent glances back and forth between eyepiece and atlas, the latter illuminated by a dim red light, will soon tell you how much sky

appears in the eyepiece at one time. Recent psychological studies of pattern recognition have shown the importance of orienting the chart to match the visual field This is easy when a region near the meridian is viewed in a refractor, but some care may be needed with a reflector, or if the region is far from the meridian.

The job of locating faint deep-sky objects is always made easier if there are nearby finder stars. Since most telescopes have a field of view less than 1° j_ndiameter when used at lOOx (a good magnification for searching out many small objects), it would be nice to have charts with at least one star in each l°-diame-ter field. You can test your own charts by cutting the correct size circle in a piece of paper and moving it around the charts to see how often there are no stars showing in the 1° opening.

Figure 12.5 The energetic nucleus of the Seyfert galaxy M77 in Cetus is spewing out clouds of gas (each with the mass of about 10 million Suns) at speeds of nearly 400 miles per second.

The galaxy M77 in Cetus is a good practice object near a naked-eye star (Figure 12.5). Put on a low-power eyepiece and center Delta (8) Ceti in the field (perhaps after sighting along the side of the telescope tube). Then, by remembering how large the !4° Moon looks in the same ocular, slide the telescope an estimated 1 southeast. A small, steady glow seen in this region will probably be M77.

If this attempt fails, put Delta back in the center of thc field, then wait 3.2 minutes — the difference in right ascension between Delta and M77 — and scan along a north-south line. You should spot the galaxy south of where thc star had been by some 2T, the difference in their declinations.

M77 is an old friend from my days in Kansas. Even under 400x in my 10-inch reflector, I could never quite distinguish the starlike nucleus that some observers have reported. In viewing extended deep-sky objects, maximum image contrast is essential to discern small differences of tone. But any stray light in the optical system (from dirty or imperfect lenses), sky brightness, or artificial light will compress the scale of recognizable shades by eliminating black and lightening all grays. Light that does not go into the image goes elsewhere to brighten the field. The result is a washed-out image, and near the limit of visibility it may mean the difference between seeing or not seeing the subject.

This fact was emphasized one night when 1 was observing M77 with thc 4-inch Clark refractor. The night was good and the Milky Way especially vivid. Normally, M77 appears as a round patch of light 2' in diameter, fading irregularly near its edge. This night, however, the edge of the galaxy was sharply seen against the background. Also, for thc first time in so small an instrument, I could see mottling in its core. Thc excellent optics and the fine night changed this minor galaxy into a marvelous sight, rivaling much more popular objects.

The Skalnate Pleso Atlas Catalogue puts M77’s visual magnitude at 8.9 and photographic at 9.6. But the Revised New General Catalogue (RNGC) gives 10.5 photographic for it. Such discrepancies between catalogs are not at all unusual, emphasizing the fact that magnitudes assigned to nebular objects depend strongly on the size and type of instrument and the method of observing. Galaxies are roughly one magnitude fainter in blue light (photographic) than in yellow-green (visual). Also an estimate of a galaxy’s magnitude is apt to be brighter with a small telescope than a large one. This effect was noted long ago by comet observers. It is particularly marked for very extended objects of low surface brightness.

M77 inspired a remarkable set of seesaw descriptions by early observers. The galaxy was discovered in October 1780 by Pierre Mechain. Although Mechain initially described it as a nebula, that December Messier called it “a cluster of small stars which contains some nebulosity.” The observation that really surprised me, however, was William Herschel’s in the early 19th century. This skilled observer called M77 “a cluster of stars ... [with a] stellar appearance when it is viewed in a very good common telescope.” (Keep in mind that a common telescope in Herschel’s day was not very good when compared with the average equipment owned by amateurs today.) His son John called M77 “partly resolved.”

At this point one might rightly ask, what gives? Does M77 look like stars or nebulosity? The pioneering English astrophotographer Isaac Roberts indirectly offers a possible answer to the discordant visual descriptions. In the late 1800s his photographs revealed M77 to be a stellar nucleus surrounded by nebulosity “studded with strong condensations resembling stars.” Could others have seen these condensations as stars? I had one such view, but it was with a 36-inch reflector back in the 1930s, and other visual descriptions made with similar-size instruments make no mention of the “stars.” Thus, with proper reverence for Messier and his contemporaries, we must erase any idea that M77 can be resolved like a star cluster.

There’s no question, on the other hand, that the galaxy has a bright nucleus. M77 is in fact among the brightest examples of a Seyfert galaxy, one having a miniature quasar at its core.

Galaxy Chains in Cetus

lust as open clusters dominate our view of the starry band of the Milky Way, galaxies tend to be most numerous in those parts of the sky farthest from this region, where dense star clouds and obscuring dust can block our view of deep space. Such is true for the constellation Cetus, now in the evening sky. "It is a vast stellar desert," Scotty wrote, "but a rich area for galaxy hunters." Amateurs equipped with only a 3-inch or 4-inch telescope can pick out many galaxies, and a 12'Z>-inch will show many more of them. Here Scotty describes a series of galaxy chains in Cetus and a mysterious planetary nebula that should keep novices and seasoned observers busy during the long December nights.

For those who want to sweep the field around M77, several other galaxies are within the range of amateur telescopes. This is an especially good field for beginners, since the 4th-magnitude star Delta (8) Ceti provides an easy starting point just under 1° northwest of M77. The star and the moderately bright Messier object serve as landmarks to return to if you get lost while hunting for the other sights.

Some X° due north of Delta Ceti lies the faint galaxy NGC 1032. Sky Catalogue 2000.0 lists it as a spiral with photographic magnitude 13.2. A good rule of thumb is that such objects will appear a magnitude brighter visually. I’ve estimated NGC 1032’s brightness as 12.1 with the 4-inch Clark. Herschel called it “pretty bright.” This may seem strange in light of his description of nearby 10.5-magnitude NGC 1055 as “pretty faint,” but it may be due to NGC 1032's smaller size (about 3' x 1'), which increases the surface brightness of the galaxy.

This effect is also demonstrated by two other galaxies in the area. Both NGC 1073 and NGC 1087 are listed as magnitude 11.0 in Roger Sinnott’s NGC2000.0. Herschel, however, called the smaller galaxy (NGC 1087. 3.5') “pretty bright” and the larger one (NGC 1073,4.9') “very faint.” I have examined a photograph of the field, and at first glance it would seem that more than a magnitude separates these galaxies. Trying to convert from one system of brightness determinations to another can be an amateur’s nightmare.

Eight degrees south of Delta Ceti, the stars 80 and 77 Ceti mark another clump of galaxies. The three brightest are seen in my 4-inch Clark with averted vision, and once so found they can be glimpsed with only a 3-inch. First try NGC 1022, a barred spiral, l‘A° northeast of the two stars. From Louisiana, back in 1945, my 10-inch reflector showed traces of structure in this 1.4' x 1.8' oval: the night was superb but the dewing was so heavy that I had to use heaters on the main mirror to observe at all!

At my Joseph Meek Observatory, the galaxy was featureless in the 4-inch. I made its magnitude 10.8. while the RNGC gives its value as 12.5 photographically.

NGC 1052’s tiny 1' diameter bears magnification well. In a 10-inch with 200x at Milwaukee, Wisconsin, 1 once estimated it to be 11th magnitude; the RNGC makes it 12.0 in blue light. About equally dim is NGC 1084, a distinct oval 2' long.

Those equipped with large amateur instruments may want to fill out the grouping with a trio of very faint galaxies.

Even a 10-inch will pick up NGC 991 with little trouble. This is a roundish galaxy less than 2' across and ²A° north of 80 Ceti. According to the catalog, its photographic magnitude is 12.5.

NGC 1048 lies %° south of NGC 1052 and slightly west. Decidedly cigarshaped, it is 4' long and looks about 12th magnitude. The RNGC lists it as a close pair of galaxies, each of photographic magnitude 14.0.

Using lOOx or more, try your luck with NGC 1035, a sliver 2' long (between 80 Ceti and NGC 1052). Here, the photographic magnitude and my visual impression are both 13.

The last three are atmospheric test objects for us in the United States, and even more so for Canadians, where these galaxies culminate somewhat lower in the southern heavens.

Northeast of 4th-magnitude Theta (0) Ceti is a chain of four galaxies just right for 6- to 8-inch telescopes. The chain extends northwest to southeast. The northernmost galaxy is NGC 584, an elliptical whose slightly oval disk is a bit less than 2' across with a visual magnitude of 10.8. It has been seen with a 2‘Z-inch aperture and shows well in my 4-inch Clark refractor. If you are using a large instrument, try looking for 14th-magnitude NGC 586 just 5' to the southeast.

The next galaxy in the chain, 25' southeast of NGC 584, is NGC 596, which lies just west of a faint naked-eye star. The best view of this 11.5-magnitude elliptical will be had if the relatively bright star is kept out of the field. It may also help to rock the telescope gently, as slight motion sometimes improves the visibility of faint objects. I have found that the rocking technique works well when 1 am viewing extended objects like galaxies, but just the opposite is true for stars — the least field motion will wipe out faint stars.

About !6° southeast of NGC 596 is NGC 615. It is a spiral galaxy about 2' long with roughly the same brightness as NGC 596. NGC 615 has a distinctly bright nucleus that seems displaced from the center of the galaxy. This object was easy for my old 10-inch reflector in Kansas.

The last galaxy in the chain is NGC 636. It is about 1° from NGC 615 and displaced slightly to the east of a line connecting the other three. 1 estimate this faint elliptical to be magnitude 12.0 and just under 1' across. NGC 636 looks very much like a small planetary nebula. When I placed an ultrahigh-contrast (UHC) filter between the eyepiece and my eye, however, the object dimmed along with the stars, thus ending any thought that it was a nebula.

246 (with four stars superimposed on it) appears bright and round in large telescopes.

etary NGC 246. Flipping the filter in and out of the view caused the stars to blink while the nebula remained conspicuous. In my opinion filter flipping is a much better way to locate small planetaries than the older method of using a prism or spectroscope.

NGC 246 was discovered by William Herschel, who called it large and very faint. I question his description of it as faint, since I can see it with the 4-inch Clark. Modern estimates placed the 4'-diameter planetary at magnitude 8.5. Ronald Morales saw NGC 246 “well” in a 6-inch reflector. With an 8-inch f/5 reflector, he reports that the nebula was “easily seen as a round, diffuse glow behind three stars of similar brightness. A fourth was glimpsed, but the central star was not seen.” Other reports suggest that the planetary is a complete ring in apertures larger than 10 inches, while smaller instruments show the ring as broken.

If you are interested in hunting out some of Cetus’s fainter galaxies, begin with NGC 309, located about 3° northeast of NGC 246. It is a 12.5-magnitude spiral about 2' in diameter. Objects like this show better in long-focus instruments since they tend to scatter less light in the field. My old 10-inch reflector was f/8.6, and it gave fine views of faint deep-sky objects. Some of my best deep-sky views have been with the Stellafane 12-inch Porter turret telescope, which is f/17.1 also suggest using a Barlow lens to obtain higher magnification. A low-power eyepiece and Barlow seem to scatter less light and produce a higher-contrast view than a high-power eyepiece alone.

Less than 1° northeast of NGC 246 is NGC 255, another spiral that is about the same magnitude and slightly larger than NGC 309.1 have glimpsed it with the 4-inch Clark, but a 10-inch would be a more practical instrument to fish it out.

Lastly, there are two faint galaxies about 3° southwest of NGC 246. The brighter is the spiral NGC 210. Its oval disk is about 4' long and catalogs list it a^s magnitude 11.8. While in Louisiana during World War II. I had a fine view of this object with the 10-inch reflector. Less than 1° to the southwest is NGC 178, which was also visible in the 10-inch. However, at 13th magnitude and about 1' in diameter it is a more challenging object.

Another Cetus galaxy, NGC 578, seems never to have been mentioned in this column before, nor is it plotted in Norton’s Star Atlas, but over the years I have seen it several times with apertures ranging from 13 inches down to 4. With averted vision, look a for a dim oval glow, about 4' by 2' in extent. It is best to prepare a finder chart by plotting this position on a map showing stars as faint as magnitude 9, for this object is very difficult to acquire by simply sweeping. If you don’t find NGC 578, you have the consolation that William Herschel missed it too. My estimate of the total magnitude is about 11.2, as seen in the 4-inch.

By the way, I would like to thank all the people at the 1990 Stellafane convention in Vermont who participated in the “Hello, Scotty!” greeting on Saturday evening. That shout may have made it all the way to Connecticut (I’ve learned of unusual happenings in the area that were glibly attributed to weather conditions), but at the time I was enjoying a meal of delicious mussels at a sidewalk cafe in Belgium following the AAVSO’s European meeting. It was the first Stellafane I’ve missed in many years.

A Romp in the December Wonderland

"It is December again and the stars have an extra snap and sparkle. The humidity is down, objectives do not dew up, and the warmly dressed observer is as happy as on June nights." Or so Scotty thought when he wrote from Kansas in 1955. Nearly four decades later he noticed that the skies had steadily deteriorated and wondered what our skies would be like in the future. Despite this growing nemesis, which we now commonly refer to as light pollution, the night sky with all its splendors continues to inspire passionate souls. In this last installment, Scotty takes us on a visual romp to some of December's most astonishing sights, all of which have been covered in more detail throughout this book. Still, they are, as Scotty has called them, the old favorites of our youth. The romp ends with M42, the Orion Nebula. Thus the book comes full circle. In the end, when called upon to reflect on the importance of amateur astronomy, Scotty looked into his crystal ball and saw the promise of progress, mainly because in his heart he cherished a belief in the positive impact of the night sky on the affairs of humanity.

Fifty years ago, any kid in a big city like my old hometown of Milwaukee could set up a telescope in his or her backyard and enjoy really first-rate views of the night sky. This is far from the case today, and the problem facing most urban observers is to find a dark-sky site that can be reached quickly with a telescope that can be stuffed into the back of an automobile. Long-time author and telescope maker Robert E. Cox once noted that amateur telescopes in the 1930s

The open cluster M38 (top) and its smaller companion NGC 1907 (bottom) both lie in Auriga.

stayed collimated better than those of today. One reason may be that years ago we didn’t drag our equipment over so many back roads.

As many of us know, the telescope is a wondrous invention, and the heavens contain all manner of marvels that can still astound the imaginative mind, no matter what the smog density may be. Some of the better sights await us in the December evening sky. The Northern Cross is erect in the northwest: Albireo has already set. Pegasus is now a great diamond-shape sloping slowly to the west, as Orion mounts closer to the meridian. This is no time for routine or difficult objects: it is better that we sweep again the old favorites of our youth — the sights that enthralled us with our first homemade reflector.

The Pleiades must come first, that marvelous cluster which in opera glasses is more splendid than most galactic clusters in a 10-inch. But if we have a 10-inch the splendor may keep us at the eyepiece for long moments. Perhaps we can faintly see the Merope Nebula — it is not impossible. Next we pause for a brief glance at the Hyades, bright with piercing sparkle.

After this comes the great Double Cluster in Perseus. To the naked eye it shines with a steady glow between Cassiopeia and Perseus, and in the telescope this tremendous blaze of scintillating suns makes a commanding entrance into the eyepiece field. One can look for a long time at the many doubles, the colors, the winding patterns as the dense cores of the cluster thin out slowly to merge finally into the star-rich background of the galaxy itself.

Moving down the Milky Way we run into such variegated star fields and clusters in Auriga that it is almost impossible to know where to halt, but this might very well be at M38. Evenly compressed into a glowing ball two thirds the diameter of the full Moon are over 100 softly blazing stars (Figure 12.7). Nearby >^s M36, a rich cluster of fainter stars, somewhat smaller but also impressive. It is well to trail the telescope slowly over the whole length of the Milky Way in Auriga, for objects unmentioned in these regions would be major sights in most other parts of thc sky.

Farther to the south, we pause for a moment at Ml. the famous Crab Nebula, although our telescopes will show little more than an oval glow, with little trace of wispy filaments. Less well-known, but still one of my favorites, is the diffuse nebula M78 in Orion, with a few stars apparently superimposed. It has a curious “ink-blob” symmetry.

Next in numerical order is M79 in Lepus, an 8th-magnitude globular cluster eight arcminutes in diameter. Finally, saving the most impressive for last, is the incomparable M42, the great Orion Nebula, about which words fail. No amount of intensive gazing ever encompasses all its vivid splendor.

Fortunately most amateurs don’t bother with the semantics of their title. But it seems appropriate to consider what the name means. For starters 1 turned to the New English Dictionary. This scholarly work informed me that the word “amateur” is rather new to the English language, having appeared in print sometime after 1700. It is taken from a French word meaning “lover.” In thc 1700s, to be an amateur simply meant loving a subject. The word was used in bird-watching, lichen counting, painting, and all such sorts of human devotion. The connotations were always favorable.

Shortly after 1800 a derisive use began to appear. And in astronomy the modern division began to form between admiration for the stars and earning a living. The separation between amateur and professional astronomers became wide and deep. In the 1880s, when New York amateur astronomer and newspaper writer Garrett P. Serviss formed an organization called the American Astronomical Society, Simon Newcomb of the Nautical Almanac Office loudly protested that no amateur group should be allowed to carry so lofty a name.

Other professionals were less disapproving. Edward C. Pickering of Harvard recruited amateurs to monitor variable stars, and his efforts led to the formation of the American Association of Variable Star Observers. This and other organizations helped raise the status of amateurs.

Today the observations of amateurs can redirect efforts at professional observatories around the world. Australia’s Robert Evans, observing from his backyard, has alerted professionals to many supernovae, allowing them to gather data on some very unusual stars in a timely fashion.

In 1931 Harvard astronomer Harlow Shapley gave a talk to the Milwaukee Astronomical Society (all 18 members). Afterward, during a discussion that went into the wee small hours, we talked of the role amateur astronomers play. Shapley did not see amateurs as volunteers who only did chores for the professionals. He saw them as a vital link between professionals and the public, a link that must exist if observatories hope to survive.

Lewis Epstein had a slightly different assessment of amateurs, one that he outlined in a talk before the Astronomical Society of the Pacific. He sees amateurs as the ones who plant and cultivate the seeds for the next generation of professional physicists, mathematicians, and engineers, as well as astronomers. So it’s with a great sense of pride that we, as amateurs, go outside and enjoy the night sky.

Whether listening to lectures, participating in swap meets, sharing tips on telescopes, or showing off their equipment — as shown in these scenes from the July 1987 Stellafane convention in Springfield, Vermont — amateur astronomers spread their passion for astronomy. It all comes down to the love of the night sky, which Scotty helped to foster. In 1994, the year after Scotty died, Stellafaners showed their love and affection for him with a moment of silence by candlelight. It was a fitting tribute to a man whose words helped so many grow in their own love of the sky.

Ast = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dark Nebulo; GC = Globular Cluster; Gx = Goloxy; OC = Open Cluster; PN = Planetary Nebulo; * = Sfor; * ♦ = Double/Mulliple Star; Var = Variable Star

SOURCES

Listed below by month and year of issue are the Deep-Sky Wonders columns from Sky & Telescope that were mined to create this book. Also listed are the sources who generously provided the images that accompany the text, and whose permission is gratefully acknowledged.

February 1950, January 1952, December 1955, February 1971. September 1980. January 1987. January 1991.

Horsehead: January 1952, December 1957, January 1969. January 1970, January 1979.

July 1949. January 1955. April 1955, October 1958. October 1959. January 1962. November 1962. December 1965.

Images: 1.1.1.2,1.3,1.5,1.6.1.10,1.11,1.12: Akira Fujii. 1.4: Chuck Vaughn. 1.7.1.8, 1.9: Sky & Telescope. 1.13: NGS-POSS.* 1.14: DSS-S.**

April 1954. March 1962, August 1963, February 1968. May 1968. December 1970, December 1973. December 1980. March 1985. October 1986, February 1991, November 1991. November 1993, February 1994.

February 1968, December 1973, December 1980, March 1985, February 1991, November 1991, November 1993,

December 1981, March 1982, December 1982, November 1983. November 1985, January 1987. October 1988, December

December 1947, November 1954, December 1963, May 1969, December 1976, January 1979. December 1981,

December 1947, November 1954, December 1956, November 1960, January 1964. December 1976. December 1982.

Averted Vision and the Celestial Jellyfish March 1949, February 1962, April 1964, May 1966, November 1967, May 1979, January 1980. November 1981.

Images: 2.1: Preston Scott Justis. 2.2,2.7: Martin C. Germano. 2.3,2.9: NGS-POSS. 2.4,2.5: DSS-N.*** 2.6: George Greaney. 2.8: George R. Viscome. 2.10: Akira Fujii. 2.11: Mt. Wilson and Palomar Observatories, courtesy the California Institute of Technology. 2.12: Dennis di Cicco.

April 1957, March 1960, March 1964. January 1966, March 1977, February 1980, March 1982, December 1983, February

April 1957. March 1960. March 1964. March 1977, February 1980. March 1982, February 1984, January 1985, February 1986, March 1989.

February 1961, February 1970, February 1971, February 1972, February 1980, March

The Great Corridor of Open Clusters January 1947, February 1954. December 1955, February 1960, January 1961. January 1974, February 1975. March 1977, December 1979. December 1985. January 1990

Images: 3.1: Chuck Vaughn. 3.2,3.7.3.9: Akira Fujii. 3.3: Preston Scott Justis. 3.4: John Chumack. 3.5: Sky & Telescope. 3.6: NGS-POSS. 3.8: DSS-N. 3.10: DSS-S. 3.11: Martin C. Germano.

March 1949. March 1956. March 1971, March 1975, April 1978, February 1980, February 1981. April 1984, April 1985, February 1989.

March 1976. March 1981. February 1983. March 1984, February 1985, March 1988, April 1989, March 1990. January 1993.

March 1963, February 1967. March 1 ^{1 ll}-April 1971. March 1972, April 1972. March 1978, March 1981, May 1981, February

May 1947. June 1947. May 1969. March 1970. April 1971. March 1978. March 1984. April 1984.

Images: 4.1: Preston Scott Justis. 4.2: NGS-POSS. 4.3.4.5,4.6: Akira Fujii. 4.4. 4.8: Martin C. Germano. 4.7: DSS-N.

June 1956. June 1961, May 1965. May 1970. May 1973. June 1978. May 1979. May 1981, May 1984. May 1987. May 1988, February 1992. May 1994.

May 1951. March 1962. April 1968, April 1969. March 1974. April 1976. March 1981.

April 1948. March 1954. February 1958, April 1961. April 1963. March 1973. April 1977, March 1980, April 1982, March 1983. May 1983. April 1986, April 1987, April 1988, April 1989.

April 1964. April 1970. April 1971, March 1981. April 1982. April 1984. April 1985, March 1991.April 1992.

Images: 5.1a, 5.1 b. 5.2,5.8.5.10: Akira Fujii. 5.3,5.6: NGS-POSS. 5.4.5.5: DSS-N. 5.7. 5.9: Chuck Vaughn. 5.11: Jeffrey Jones.

Images: 6.1,6.2,6.3,6.4,6.5,6.6: Akira Fujii. 6.7: Kim Zussman. 6.8: National Maritime

6.11: DSS-N. 6.12: Harvey Freed. 6.13: Martin C. Germano. 6.14: George R. Viscome.

August 1949, July 1967. May 1969, June 1969. June 1979, March 1982. July 1985. July 1986. May 1991.

MH: June 1958, June 1963, June 1976, September 1982. June 1983, January 1985, August 1986. June 1987, September 1989. July 1992, July 1993.

July 1967. August 1970. July 1971,September 1978, July 1980, June 1984. August 1984.

Images: 7.1,7.7: Martin C. Germano. 7.2,7.4, 7.8: Akira Fujii. 7.3: Mt. Wilson and Palomar Observatories, courtesy the California Institute of Technology. 7.5: From The Scientific Papers of William Parsons, Third Earl of Rosse, 1800-1867. Collected and republished by the Hon. Sir Charles Parsons, K.C.B.. F. R. S., 1926. 7.6: Roger Sliva.

August 1953, August 1962, August 1976. August 1980, July 1984, August 1987, July

September 1957, September 1963, August 1978, July 1984, July 1986, September 1986, September 1987, August 1990.

October 1956, October 1961. August 1963, August 1967, October 1980, September 1991, August 1993.

Images: 8.1: NGS-POSS. 8.2: Robert Bickel. 8.3,8.10: Preston Scott Justis. 8.4,8.6: Martin C. Germano. 8.5,8.7,8.8: Akira Fujii. 8.9: DSS-N.

August 1948, September 1948. October 1948, September 1956, August 1965, September 1968. August 1972. September 1973. October 1973. August 1980, September 1980, October 1980, September 1981. September 1982. August 1983, October 1984. December 1985. September 1989. November 1991.

September 1966, December 1967. November 1969, September 1980, August 1983, July 1984. October 1984, September 1987. December 1987.

Images: 9.1,9.2,9.5,9.7, 9.8: Martin C. Germano. 9.3: DSS-N. 9.4: Paul Lind. 9.6: Chuck Vaughn.

Two Spectacular Autumn Globulars October 1952, October 1955, September 1962, November 1974, October 1978. October 1979, October 1980, July 1982, October 1982. October 1983. November 1985. December 1985, October 1988. November 1992.

September. 1956, September 1958. August 1966. July 1979, September 1985. July 1986, September 1986.

Images: 10.1, 10.5: Akira Fujii. 10.2, 10.6, 10.10: Martin C. Germano. 10.3: Lee C.

Coombs. 10.4: DSS-S. 10.7: Mt. Wilson and Palomar Observatories, courtesy the California Institute of Technology. 10.8: NGS-POSS. 10.9: George R. Visconte.

January 1948, October 1953, October 1954. September 1967, December 1968, December 1969, November 1976, November 1981, September 1982, October 1983.

November 1946, November 1955, October 1958, January 1962, December 1976, December 1977, September 1980, November 1980, September 1981, November 1981, December 1981, November 1985, January 1986.

October 1963, November 1970. August 1971, November 1972, October 1976, November 1988. December 1991.

11.7: Martin C. Germano. 11.3,11.4, 11.10a, 11.10b: Akira Fujii. 11.6: Preston Scott Justis. 11.8: Andrew Peters. 11.9: Royal Observatory, Edinburgh.

The Challenge of the Seven Sisters October 1950, January 1967, December 1971, October 1972, January 1975, December 1976, December 1977, December

Taurus: The Observer's Paradise January 1979. December 1979. January 1981, December 1983, October 1992.

Images: 12.1,12.2.12.3.12.4: Chuck Vaughn. 12.5: Dale E. Mais. 12.6: Martin C. Germano. 12.7: Preston Scott Justis. 12.8a-h: Dennis di Cicco.

* From the National Geographic Society-Palomar Observatory Sky Survey, courtesy the California Institute of Technology.

** From the Digitized Sky Survey, Southern Hemisphere, courtesy U. K. Schmidt Telescope Unit and NASA/AURA/STScI.

*** From the Digitized Sky Survey. Northern Hemisphere, courtesy the Palomar Observatory and NASA/AURA/STScI.

This bibliography lists the books, atlases, journals, and other published materials cited in the text. If a work is currently available in a new edition, the most recent bibliographical information is given.

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Alfonsine Tables. A set of astronomical tables widely used during the Middle Ages. Named after Alfonso X. King of Castille and Leon (1252-1284).

Clusters of the RNGC, Typeset and printed in Great Britain by Don Miles, Portsmouth: The Webb Society, 1993.

Aristotle, Meteorologica. In Greek, with English translation by H. D. P. Lee, Cambridge, 1952: Cambridge University Press.

Barns, C. E„ 1001 Celestial Wonders, as observed with home-built instruments, Morgan Hill, CA. 1927: Science Service Press; released in 1929 by Pacific Science Press.

Be^var, A., Atlas Coeli 11 Katalog 1950.0 (Atlas of the Heavens Catalogue 1950.0), Prague, 1960: Ceskoslovenske Academie.

Becvar. A., Skalnate Pleso Atlas of the Heavens, Cambridge. MA. 1964: Sky Publishing Corporation.

Bonner Durchmusterung Catalog. Bonn. Germany, 1855: Universitats-Sternwarte zu Bonn.

Brocchi. D. F., AAVSO Star Atlas, Cambridge, MA. 1936: American Association of Variable Star Observers.

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Dreyer, J. L. E., New General Catalogue of Nebulae and Clusters of Stars (1888). Index Catalogue (1895), Second Index Catalogue (1908), London, 1962: Royal Astronomical Society.

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Galilei, G„ The Sidereal Messenger (Sidereus nuncius). Translated, with introduction, conclusion, and notes by

Harrington, P.. Touring the Universe Through Binoculars. New York. 1990: John Wiley & Sons.

Hartung, E. J.. Astronomical Objects for Southern Telescopes. Cambridge, England, 1968: Cambridge University Press. (Republished in 1995 as Hartung’s Astronomical Objects for Southern Telescopes, 2nd ed., rev. and illus. by David Malin and David J. Frew.)

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Jones. K. G., ed., Webb Society Deep-Skv Observer’s Handbook. Vols. 6-8, Anonymous Galaxies, Hillside. NJ, 1975: Enslow Publishers

Journal of the Royal Astronomical Society of Canada. Richmond Hill. Ontario: David Dunlap Observatory.

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National Geographic Society, National Geographic Society-Palomar Observatory Sky Survey, Pasadena. CA. 1954,1958: California Institute of Technology.

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Sulentic. J. W.. and W. G. Tifft. The Revised New General Catalogue of Nonstellar Astronomical Objects, Tucson. AZ, 1980: University of Arizona Press.

Tirion. W.. and R. W. Sinnott, Sky Atlas 2000.0, 2nd ed., Cambridge. MA. 1998: Sky Publishing Corporation and Cambridge University Press.

Tirion, W., B. Rappaport, and G. Lovi, Uranometria 2000.0, 2 vols., Richmond, VA, 1987: Willmann-Bell.

Vehrenberg, H., Atlas of Deep-Sky Splendors, 4th ed., Cambridge, MA, 1983: Sky Publishing Corporation and Cambridge University Press.

Webb, T. W.. Celestial Objects for Common Telescopes, Vol. 2. New York, 1962: Dover Publications.

Scotty loved to set challenges for observers, so it is appropriate that this distillation of his Sky & Telescope columns proved something of a challenge to index.

Scotty peppered his writing with references to past observers; how such deep-sky greats as Charles Messier; William, John and Caroline Herschel; Lord Rosse; William H. Smyth; and Thomas W. Webb described this or that object was an essential ingredient of his mix. To record every mention of the names that appear so often would have generated an unwieldy batch of index entries, so for these only a representative selection has been chosen. (The most frequently quoted of Scotty’s own correspondents have not been trimmed in this way.)

Included in this index are the use of various accessories (indexed individually) and important general tips and techniques (collected under “observing tips and techniques”). Telescope types are not indexed. Many specific instruments that Scotty and others used are indexed under the names of the observatories where they are located. Not included are Scotty’s own telescopes — he mentions his trusty 4-inch Clark refractor far too often.

In a sense, every Deep-Sky Wonders column threw out tests to its readers. A selection of these have been indexed under “challenges," along with a variety of targets historically regarded by amateur astronomers as tests of either their observing skills or equipment. (Many of these objects have been rendered less daunting over the years by advances in amateur telescope technology.) The “challenges” entry, along with some others that contain a dozen or more page references, has not been divided into subentries.

Every deep-sky object Scotty describes in the book is indexed here under its most familiar label. Thus, for example, the main entry for the Orion Nebula is under that name, rather than M42 or NGC 1976; such catalog numbers will also be found as cross-references. Stars mentioned in the text simply as guideposts are not indexed. There are no generic entries for types of deep-sky objects, such as spiral galaxies or dark nebulae. Again, this would have made for a number of unwieldy entries.

Object designations such as Theta (9) Orionis, FI Hydrae, and 19 Lyncis, which contain the genitive form of a constellation name, are indexed under thc constellation, in these cases under Orion. Hydra, and Lynx. Each constellation entry starts with the numbers of pages on which these and differently designated objects in that constellation are described.

Page numbers in boldface refer to photographs or illustrations and their captions. Numbers in italics refer to the tables of objects at the end of each chapter. The suffix n indicates a footnote.

Altair (Alpha Aquilae) see Aquila Alvan Clark & Sons, 6n amateur astronomy, 277-8 development of, 39-40,49,50-52, 105-7,114,155-6,211,219

astrophotography, 6-7, 111, 226 photographs vs. visual appearance, 3,5-6,8,38,43,110, 111,125,134,142,153,158, 160,163,180-81,209,227. 246,263

Cor Coroli (Alpha [ex] Canum Venaticorum), 132; see also “Deep-Sky Triangle”

catalogs, descriptions in vs. visual appearance, 12-15,29,36,55-6, 80,103,116-17,173,174.229,246, 251,266,271,272

Dearborn Observatory, 61 deep-sky filters see nebula filters “Deep-Sky Triangle” (Eta [r|] Ursae Majoris. Alpha [oc] Canum Venaticorum, Gamma [y] Bootis), 129.130

Alpha (a) Delphini, 189. 792 Beta (P) Del, 82,96,188-9, 792 Gamma (y) Del. 188,792 Theta (6) Del. 191,193

Deneb (Alpha Cygni) see Cygnus Denning, William, 29,263 di Cicco, Dennis, 18, 159

Nagler, 113,224 occulting bar in, 114 orthoscopic, 35 Plossl, 54,153,207 wide-field, 19,54

Herschel. William, 3-4, 15, 49, 50, 52, 58,67,76,83-4,92,111,137,137, 205-6,266-7,271

Hyades (Melotte 25), 265,276,281 Hydra, 89-95: FI Hydrae, 92,96 “Hydra Hysteria," 89-93

Machholz, Don, 89,126 magnitudes of deep-sky objects, reasons for differences in, 271

217.241,247.257.277 boundaries, 184-5.186 in Eastern legend, 258 individual stars, visibility of, 86 as naked-eye object, 256

13-inch reflector. 39.40,55,235 "missing” objects see “nonexistent” objects

12 Monocerotis, 50 Morales, Ronald, 44,78,91,95, 111, 115,116,131,135,143,145. 156-7,166,167,191,245,252, 253,274

naked eye, faint objects visible to, 10-11,49,52-3,63,80,84-5,86, 139,161,181.218-19,223,224-5, 256,264

O 111,6,34,84,199.213,224 ultrahigh-contrast (UHC), 6,49, 51-2,95,201,207.208.232, 273

NGC 2281,68. 72

NGC 2287 see M41

NGC 2292,64,64. 72

NGC 2293,64.64. 72

NGC 2295, 64.64. 72

NGC 2300,173-4.192

NGC 2403, 27-9, 28.47

NGC 2410,61, 72

NGC 2419.76,76-7,96

NGC 2469, 84, 96

NGC 2474,83,96

NGC 2475,83,96

NGC 2500,78, 96

NGC 2537,78,96

NGC 2541,78,96

NGC 2548 see M48

NGC 2549,78,96

NGC 2552,79,96

NGC 2610.90,91,96

NGC 2632 see Beehive

NGC 2642,90,96

NGC 2667A, 88,96

NGC 2667B. 89,96

NGC 2672.88,88.96

NGC 2673,88,88.96

NGC 2677,89.97

NGC 2682 see M67

NGC 2683,77,97

NGC 2713,90,97

NGC 2749,88,97

NGC 2763,91,97

NGC 2764,88,97

NGC 2781,91,97

NGC 2782,79,97

NGC 2787,81,97

NGC 2793,78,78.97

NGC 2811,91. 97

NGC 2831,77-8,97

NGC 2832, 77. 78. 97

NGC 2844, 79. 97

NGC 2848.91,97

NGC 2851,91.97

NGC 2855,91.97

telescopes, choice of, 242 see also averted vision occulting bar see under eyepieces Olcott, William Tyler, 114,140 O'Meara, Donna Donovan, 186 O'Meara, Stephen J., 86 Omega Centauri, 99.100,101,102,122 Ophiuchus, 162-7

Owl Nebula, 124,124,148 Oyster Nebula (NGC 1501), 29,30,47 Palomar Mountain Observatory

Peterson, Harold, 10 photography see astrophotography Pickering. Edward C„ 277 Pickering, William H., 5

sky conditions, 17,35,82,84,185-6 measures of, 19.38,53,84-5,174, 218,236,246,261,263,273 see also atmospheric absorption

Smyth, William H„ 3,18,54,65,88.90, 94,110, 111, 128,153,158,160-61, 200,206,222,243

southern objects visible to northern observers, 19-24,41-4,68-71,93, 99-102,233-8,251-6

Porter turret telescope, 12-inch, 19,117,125,159,181,183, 203,219-20,226,274,243 Stephan. Edouard, 182,186 Stephan's Quintet (NGC 7317,7318A,

Summer Triangle. 185,210.211.257 Sunflower Galaxy (M63), 132.132.147 Swift. Lewis, 23,50.91,113

Tennyson. Alfred. Lord, In test objects see challenges tests see sky conditions, visual acuity Texas Star Party, 34,151, 170.208.

U. S. Naval Research Laboratory, 45 ultrahigh-contrast (UHC) filters see nebula filters

Virgo, 137-9,145-6 visual acuity, 10,45,52,63,206 binocular vision, 232 effect of cataract surgery, 94-5,

Wesleyan University (Van Vleck Observatory), 20-inch refractor, 91,111,116,142,161,164.169, 181.225,228.242

Walter Scott Houston was an amateur's amateur, a man who could grind a mirror as well as he could estimate the magnitude of a cataclysmic variable or explain how to see dim details in a galactic nebula. Scotty, as he was known to everyone, was a groundbreaker and a ground shaker — generally the first to announce an observing trend and predict its promise or demise. He filled his Deep-Sky Wonders columns with observational magic and fueled the imaginations of countless skywatchers.

Scotty was referring to the poem Locksley Hall by Alfred, Lord Tennyson. One stanza in particular is a favorite of stargazers:

From Serviss's 1901 book Pleasures of the Telescope. Serviss was a well-known science popularizer and early science-fiction writer.

Renowned optical firm Alvan Clark & Sons of Cambridge, Massachusetts, supplied finely crafted telescopes to both amateur and professional astronomers from 1850 to 1958.

The National Geographic Society-Palomar Observatory Sky Survey is an atlas of 1,830 photographs taken with the 48-inch Schmidt telescope on Palomar Mountain.

Now out of print, this atlas, compiled by Antonin Begvar and his colleagues at the Skalnate Pleso Observatory (in the former Czechoslovakia), was first published in 1948 under the Latin name Atlas Coeli 1950.0. Sky Publishing released it with an English title in 1962. Its successor is Sky Atlas 2000.0 (now in its second edition) by Wil Tirion and Roger W. Sinnott.

The Alfonsine Tables comprise some of the earliest-known lists of planetary positions for various dates, based on Ptolemy's models of planetary motions. They were named after the 13th-century King Alfonso X of Leon and Castile, a devoted patron of astronomy.

The closest point of approach of two stars during their orbit around their center of mass.

mentioned earlier. The planetary is slightly oval and about 8" long (Figure 9.3). Although it should be visible in a 6-inch telescope, larger apertures will make the ^lask of locating this object easier. Il will show as a disk at magnifications of lOOx ^Or more. There is a central star of magnitude 14.6, but 1 know of no amateur sight-^ln8^s of it. With a Lunticon O III filter I have seen IC 5217 with the 4-inch Clark.

There are no bright Lacerta galaxies, but NGC 7331 lies just over the line in ^egasus. It is a lOth-magnitude spindle about 10' x 2' in extent. A 2-inch finder ^^veals it with effort, but it shows well in my 5-inch Japanese binoculars. NGC

I is of current astronomical interest because of a possible link with Stephan’s

■ • -------	■---------------------------------------------
• •	• • • •-		Figure 5.9 The largest and brightest galaxy in Leo Minor, 10th-magnitude
	•		NCC 3344,
		•	displays a tight core with loose
	W -	•	ly wound spiral
• • •	• • • • •		arms.

NGC 3115 O	. d Hydrae .
	■? y

■ ' ■ ' '	•'A ■ , •? V-'’
X Hydrae

Nome	Type	Const.	R. A. h m	Dec. o <	Millennium Star Allas	Uranometria 2000.0
Abell 1367	Gx	Leo	11 44.5	+19 50	—	—	—
"IC591	Gx	Leo	10 07.5	+12 16	732	189	—
Leo 1	Gx	Leo	10 08.5	+12 18	732	189	13
Leo II	Gx	Leo	11 13.5	+22 09	681	146	—
'M65TnGC3623	Gx	Leo	11 18.9	+13 05	729	191	13
"mmTnGC 3627	Gx	Leo	11 20.2	+12 59	728, 729	191	13
M95, NGC 3351	Gx	Leo	10 44.0	+11 42	730	190	13
'M96JtGC 3368	Gx	Leo	10 46.8	+11 49	730	190	13
M105, NGC 3379	Gx	Leo	10 47.8	+12 35	730	190	13
NGC 2859	Gx	LMi	09 24.3	+34 31	641	103	6
NGC 2903	Gx	Leo	09 32.2	+21 30	686, 710	143	6
NGC 2905	Gx	Leo	09 32.2	+21 31	—	—	—
NGC 3003	Gx	LMi	09 48.6	+33 25	639, 640, 661, 662	104	6
NGC3021	Gx	LMi	09 51.0	+33 33	639, 640, 661,662	104	6
NGC3130	Gx	Leo	10 08.2	+09 59	732	189	—
NGC3158	Gx	LMi	10 13.8	+38 46	638	72,104	6
NGC3162	Gx	Leo	10 13.5	+22 44	684	144	6
NGC3163	Gx	LMi	10 14.1	+38 39	633	72,104	—
NGC3177	Gx	Leo	10 16.6	+21 07	684, 708	144	6
NGC3184	Gx	UMa	10 18.3	+41 25	617	72	6
NGC3185	Gx	Leo	10 17.6	+21 41	684	144	6
NGC3190	Gx	Leo	10 18.1	+21 50	684	144	6
NGC3193	Gx	Leo	10 18.4	+21 54	683, 684	144	6
NGC3245	Gx	LMi	10 27.3	+28 30	660	105,145	6
NGC 3294	Gx	LMi	10 36.3	+37 20	637	105	6
NGC3344	Gx	LMi	10 43.5	+24 55	682	145	6
NGC 3384	Gx	Leo	10 48.3	+12 38	730	190	13
NGC3389	Gx	Leo	10 48.5	+12 32	730	190	13
J1GC 3395	Gx	LMi	10 49.8	+32 59	637,659	105	6
NGC3396	Gx	LMi	10 49.9	+32 59	637, 659	105	6

Nome	Type	Const.	R. A. h m	Dec. o /	Millennium Star Allas	Uranometria 2000.0	E S
NGC 3414	Gx	LMi	10 51.3	+27 59	659	105,145	6
NGC 3486	Gx	LMi	11 00.4	+28 58	658	105,106	6
NGC3504	Gx	LMi	11 03.2	+27 58	658	106,146	6
NGC 3588	Gx	Leo	11 14.0	+20 24	681,705	146	£
NGC 3593	Gx	Leo	11 14.6	+12 49	729	191	13
NGC 3628	Gx	Leo	11 20.3	+13 36	728, 729	191	13
NGC 3842	Gx	Leo	11 44.0	+19 57	703	147	6,13
NGC 6822	Gx	Sgr	19 44.9	-14 48	1339, 1363	297	16, 22
Omega (<o) Centauri, NGC5139	GC	Cen	13 26.8	-47 29	953	403	21,25 ~
Spindle Galaxy, NGC3115	Gx	Sex	10 05.2	-07 43	804	279	13 '

Name	Type	Const.	R. A. h m	Det. o /	Millennium Star Atlas	Uranometria 2000.0	SkyAtla^ 2000.0
NGC4027	Gx	Crv	11 59.5	-19 16	846, 847	327, 328	13,21
NGC4036	Gx	UMa	12 01.4	+61 54	559, 560	25,47	2 """
NGC4041	Gx	UMa	12 02.2	+62 08	559 560	25	2 ~~
NGC4147	GC	Com	12 10.1	+18 33	702	148	~T14 '
NGC41 S3	Gx	Com	12 10.8	+18 22	—	—	—
NGC4217	Gx	CVn	12 15.8	+47 06	592	74	2,6 "
NGC4361	PN	Crv	12 24.5	-18 48	845	328	13,21
NGC4605	Gx	UMa	12 40.0	+61 37	558	25,48	2
NGC 4782	Gx	Gv	12 54.6	-12 34	820	284	14
NGC 4783	Gx	Crv	12 54.6	-12 33	820	284	14
NGC 4792	Gx	Crv	12 55.1	-12 30	820	284	—
NGC4794	Gx	Crv	12 55.2	-12 37	820	284	—
NGC4814	Gx	UMa	12 55.4	+58 21	558	48	2
NGC4868	Gx	CVn	12 59.1	+37 19	631	108,109	7
NGC 4914	Gx	CVn	13 00.7	+37 19	631	108,109	7
NGC 5005	Gx	CVn	13 10.9	+37 03	630	109	7
NGC5033	Gx	CVn	13 13.4	+36 36	630	109	7
NGC 5053	GC	Com	13 16.4	+17 42	699	150,195	7,14
NGC5195	Gx	CVn	13 30.0	+47 16	589	76	7
NGC5198	Gx	CVn	13 30.2	+46 40	589	76	7
NGC5350	Gx	CVn	13 53.4	+40 22	608	76	7
NGC5353	Gx	CVn	13 53.5	+40 17	608	76	7
NGC 5354	Gx	CVn	13 53.5	+40 18	608	76	7
NGC 5371	Gx	CVn	13 55.7	+40 28	608	76	7
NGC 5740	Gx	Vir	14 44.4	+01 41	766	243	14 _____.
NGC 5746	Gx	Vir	14 44.9	+01 57	766	243	M -
NGC 5846	Gx	Vir	15 06.4	+01 36	765	243	14__
NGC 5850	Gx	Vir	15 07.1	+01 33	765	243	14__
NGC 5866	Gx	Dra	15 06.5	+55 46	568	50	2,7_____
Owl Nebula, M97, NGC 3587	PN	UMa	11 14.8	+55 01	576	46	2,6

• %		•
				Figure 5.6
	%		•	Leo's famous
				trio of Messier
•				galaxies —
. 'nGC 3384				M95, M96, and
	•			M105 — is
\				packed into an
X	_{_}___M105			area of sky
*				slightly larger
		•		than one square
				degree. M95
NGC 3389				and M96 are
			•	spirals while
	*.			M105 is an
				elliptical system.
				NGC 3384 and
				NGC 3389 lie
				to the east of
•				M105 and form
	9		M95	a little triangle
	M96		\	with it.
			• *

		• •
	_e
	•	•
Figure 5.7				•
For some un				*
known reason,
Charles Messier
missed discov
ering NGC	• •
2903. Look	•
for this large,		y J
9th-magnitude
spiral near the
tip of the				•
Sickle, about		•		•
4° southwest		•
of Epsilon (e)		•
Leonis.			• *
		•

				•
		•	■

Figure 5.8
Search out this
clump of three				•
spiral galaxies				•
in eastern Leo.
M65 and M66			NGC 3628	•
are each like				K *
miniature	• •		—-	.*
versions of the	•
Andromeda
Galaxy, while			•
NGC 3628 is			*
seen nearly				•
edge on.			•
	•' .
				t ’
		M66
	•	\ •	M65

			* •

*
•
•
•
•
	Figure 6.12
• •	The planetary
•	nebula NGC
• • •	4361 in Corvus
• •	looks almost
•	like a galaxy —
	with what looks
4b - •	like a central
	nucleus and
• _e	arms like those
	in a barred
• •	spiral.
•
•
• •
•
•

	Type	Const.	R.A. h m	Dec. o /	Millennium Star Atlas	Uranometria 2000.0	Sky Atlas 2000.0
7n Oohiuthi **		Oph 18 05.5		+02 30	1272,1296	249	15,16, Al
^Antares. AlphoJdScorpH__ Bernard 64	Vor	Sco	16 29.4	-26 25	1397,1419	336	22
^Antares. AlphoJdScorpH__ Bernard 64	DN	Oph	17 17.2	-18 32	1371	337, 338	15,22
Barnard 259	DN	Oph	17 22.0	-19 19	1370, 1371	337, 338	15,22
Bf Ophiuchi	Var	Oph	17 06.1	-26 35	1395,1417, 1418	337	22
Cannon 3-1, PK 38+12.1	PN	Oph	18 17.6	+10 09	1248	204	15,16
Cal's-Eye Nebulo, NGC6543	PN	Dra	17 58.6	+66 38	1065,1066	30	3
Corona Borealis Cluster, Abell 2065	CGx	CrB	15 22.7	+27 43	646	112,154	—
IC4665	OC	Oph	17 46.3	+05 43	1273	203, 248	15
IC4756	OC	Ser	18 39.0	+05 27	1270, 1271	205, 250	15,16
M2, NGC 7089	GC	Aqr	21 33.5	-00 49	1286	255,256	16,17
M3, NGC 5272	GC	CVn	13 42.2	+28 23	651	109,110	7
M4, NGC 6121	GC	Sco	16 23.6	-26 32	1397, 1419, 1420	336	22
M5, NGC 5904	GC	Ser	15 18.6	+02 05	765	244	14,15
M9, NGC 6333	GC	Oph	17 19.2	-18 31	1370, 1371	337, 338	15,22
Ml 3, NGC 6205	GC	Her	16 41.7	+36 28	1158,1159	114	8
Ml 5, NGC 7078	GC	Peg	21 30.0	+12 10	1238	210	16,17
M19, NGC 6273	GC	Oph	17 02.6	-26 16	1395	337	22
M22, NGC 6656	GC	Sgr	18 36.4	-23 54	1391	340	22
M92, NGC 6341 NGC6144	GC	Her	17 17.1	+43 08	1135	81	8
M92, NGC 6341 NGC6144	GC	Sco	16 27.3	-26 02	1397	336	22
NGC6284	GC	Oph	17 04.5	-24 46	1395	337	22
NGC 6293	GC	Oph	17 10.2	-26 35	1395,1417	337	22
NGC6309	PN	Oph	17 14.1	-12 55	1347	292	15
JGC6342	GC	Oph	17 21.2	-19 35	1370, 1371	337, 338	15,22
NGC 6356	GC	Oph	17 23.6	-17 49	1370	292, 293, 337, 338	15,22

Figure 12.2
The most
obvious part
of the visual
nebulosity	*•
surrounding		•
the Pleiades	•	•
lies near	• \ • • \ •
Merope, the	■ • ' •
cluster's south
ernmost bright
member.
	• ■. •' ■ ^f '	• •
	■ •	• • •
	•		i; •

Name	Type	Const.	R. A. h m	Dec. o /	Millennium Star Atlas	Uranometria 2000.0	5
Alpha (a) Delphini	**	Del	20 39.6	+15 55	1216,1217	209	BFt"
Beta (0) Delphini	*♦	Del	20 37.5	+14 36	1217,1241	208,209	u TT"'
Della (8) Lyrae	♦ ♦	Lyr	18 53.7	+36 58	1152,1153	117,118	u TT"'
Dumbbell Nebula, M27, NGC 6853	PN	Vul	19 59.6	+22 43	1194,1195	162,163	TT"
Epsilon (e) Lyrae	*♦	Lyr	18 44.3	+39 40	1132,1153	82, 83,117	3,8
Gamma (y) Delphini	*♦	Del	20 46.7	+16 07	1216	164,209	’TiT"
IC 1296	Gx	lyr	18 53.3	+33 04	1152,1153, 1174,1175	—
IC 1470	BN	Cep	23 05.2	+60 15	1070	34,58	~3 ’
NGC 40	PN	Cep	00 13.0	+72 32	24	3,15	1,3
NGC188	OC	Cep	00 44.0	+85 20	2,5,6,1035	1,2	1,3
NGC2276	Gx	Cep	07 27.0	+85 45	1,3,4, 518,522	1	1
NGC2300	Gx	Cep	07 32.0	+85 43	1,3,4, 518,522	1	1
NGC6217	Gx	UMi	16 32.6	+78 12	1046	11	2
NGC6700	Gx	lyr	18 46.0	+32 17	1175	117	—
NGC6713	Gx	Lyr	18 50.7	+33 57	1153	117	—
NGC6891	PN	Del	20 15.2	+12 42	1242	208	16
NGC6905	PN	Del	20 22.4	+20 07	1217	163	9,16
NGC6928	Gx	Del	20 32.8	+09 56	1241	208, 209	—
NGC6934	GC	Del	20 34.2	+07 24	1265	208, 209	16
NGC6939	OC	Cep	20 31.4	+60 38	1074.1075	32, 55,56	3__
NGC 6946	Gx	Cep	20 34.8	+60 09	1074.1075	32,56	3__
NGC6956	Gx	Del	20 44.0	+12 31	1240	209	—
NGC7006	GC	Del	21 01.5	+16 11	1215 209, 210	164,165,	9,16,17
NGC7023	OC+BN	Cep	21 00.5	+68 10	1061	32,33	3__,
NGC7129	OC+BN	Cep	21 41.3	+66 06	1060	33	3___
NGC7142	OC	Cep	21 45.9	+65 48	1060	33	-___
NGC7380	OC+BN	Cep	22 47.0	+58 06	1071	58	3___
NGC7510	OC	Cep	23 11.5	+60 34	1070	34, 58	3
As! = Asterism; BN = Bright Nebula; CGx = Cluster of Galaxies; DN = Dark Nebula; GC = Globular Cluster; Gx = Goloxy, OC = Open Cluster; PN = Planetary Nebula; * = Star; * * = Double/Mulfiple Star; Vor = Variable Star

	Type	Const.	R. A. h m	Dec. o /	Millennium Star Atlas	Uranomelrio 2000.0	Sky Atlas 2000.0
Polaris, Alpha (a) U_r$ae Minor is___ polorissimo, NGC3172	**	UMi	02 31.8	+89 15	1,2,517, 518,1033	1,2	1,2,3
	Gx	UMi	11 50.0	+89 07	1,517,518, 1034	1,2	—
King Nebulo, M57, NGC 6720	PN	Lyr	18 53.6	+33 02	1152,1153, 1174,1175	117	8
Struve 1694	*♦	Com	12 49.2	+83 25	520	9	2
Struve 2923	*♦	Cep	22 33.3	+70 22	1048	34	3
Struve 2924	*♦	Cep	22 33.0	+69 55	1048	34	3
lheto (6) Delphini	*	Del	20 38.7	+13 18	1241	209	16
Vego, Alpha (a) Lyrae	**	Lyr	18 36.9	+38 47	1132,1153	82,117	3,8
Zeta iy Lyrae	**	Lyr	18 44.8	+37 36	1153	117	3,8

Name	Type	Const.	R.A. h m	Dec. o /	Millennium Sfor Aflos	Uranometria 2000.0	sky Ati_or~n 2000 n
8 Lacertae	♦ ♦	Lac	22 35.9	+39 38	1122,1142	87,123	9
52 Cygni	**	Cyg	20 45.7	+30 43	1169	120	9
Barnard 168	DN	tyg	21 53.2	+47 12	1104,1105	86	9 '
Cocoon Nebulo, IC 5146	OC+BN	Cyg	21 53.4	+47 16	1104	86	~9
IC 1318	BN	Cyg	20 22.2	+40 15	1127 1128, 1148.1149	84, 85, 119,120	8,9
IC 1434	OC	Lac	22 10.5	+52 50	1086	57
IC 5217	PN	Lac	22 23.9	+50 58	1086,1102, 1103	57,87	9
M29, NGC 6913	OC	Cyg	20 23.9	+38 32	1127,1128, 1148,1149	84,85, 119,120	9
M39, NGC 7092	OC	Cyg	21 32.2	+48 26	1104,1105	86	9
NGC6803	PN	Aql	19 31.3	+10 03	1244	206, 207	16
NGC6804	PN	Aql	19 31.6	+09 13	1244,1268	206, 207	16
NGC6811	OC	tyg	19 38.2	+46 34	1109,1110	83,84	8,9
NGC6819	OC	Cyg	19 41.3	+40 11	1129	84	8,9
NGC 6826	PN	Cyg	19 44.8	+50 31	1091,1109	55,84	3,8,9
NGC 6866	OC	Cyg	20 03.7	+44 00	1128	84	8,9
NGC6871	OC	Cyg	20 05.9	+35 47	1149	119	8,9
NGC6894	PN	Cyg	20 16.4	+30 34	1171	119,120	—
NGC6910	OC	Cyg	20 23.1	+40 47	1127,1128	84,85	8,9
NGC6946	Gx	Cep	20 34.8	+60 09	1074,1075	32,56	3
NGC6979	BN	Cyg	20 51.0	+32 09	1169	120	9
NGC6997	OC	Cyg	20 56.5	+44 38	—	—	— __,
North America Nebulo, NGC 7000	BN	Cyg	20 58.8	+44 20	1106,1126	85	9
NGC7209	OC	Lac	22 05.2	+46 30	1103	87	9
NGC7243	OC	Lac	22 15.3	+49 53	1103	57,87	_V—-
NGC7245	OC	Lac	22 15.3	+54 20	1086	57
NGC7296	OC	Lac	22 28.2	+52 17	1085, 086	57,58
NGC7331	Gx	Peg	22 37.1	+34 25	1142	123	9 ___

Nome	Type	Const.	R. A. h m	Dec O f	Millennium Star Alios	Uronometrio 2000.0
H20	OC	Sge	19 53.1	+18 20	1219	162	8,16
Helix Nebulo, NGC7293	PN	Aqr	22 29.6	-20 48	1355,1379	347	23
"71459	Gx	Gru	22 57.2	-36 28	1423	384, 385	23
"1( 4997	PN	Sge	20 20.2	+16 45	1217,1218	163, 208	9,16
"1( 5269	Gx	PsA	22 57.7	-36 02	1423	384, 385	—
1(5271	Gx	PsA	22 58.0	-33 45	1423	384, 385	23
1( 5273	Gx	Gru	22 59.5	-37 42	1423	384, 385	23
"m2JIG(7089	GC	Aqr	21 33.5	-00 49	1286	255, 256	16,17
Ml 5, NG(7078	GC	Peg	21 30.0	+12 10	1238	210	16,17
"M30, NGC7099	GC	Cop	21 40.4	-23 11	1381, 1382	345, 346	23
M71, NGC 6838	GC	Sge	19 53.8	+18 47	1219	162	8,16
M72, NGC 6981	GC	Aqr	20 53.5	-12 32	1336	299	16
M73, NGC 6994	OC	Aqr	20 59.0	-12 38	1335, 1336	299	16
NGC1	Gx	Peg	00 07.3	+27 43	150	89,125	—
NGC 2	Gx	Peg	00 07.3	+27 41	150,174	89,125	—
NGC 16	Gx	Peg	00 09.1	+27 44	150	89,125	4,9
NGC6802	OC	Vul	19 30.6	+20 16	1220	161,162	—
NGC 6879	PN	Sge	20 10.5	+16 55	1218	163, 208	9,16
NGC 6886	PN	Sge	20 12.7	+19 59	1218	163	9,16
NGC 6902	Gx	Sgt	20 24.5	-43 39	1451, 1452	411,412	23
NGC6912	Gx	Cop	20 26.9	-18 38	1361	343	—
NGC7172	Gx	PsA	22 02.0	-31 52	1404	383	—
NGC7173	Gx	PsA	22 02.0	-31 58	1404	383	—
NGC 7174	Gx	PsA	22 02.1	-31 59	1404	383	—
NGC7176	Gx	PsA	22 02.1	-31 59	1404	383	—
NGC7410	Gx	Gru	22 55.0	-39 40	1445	384, 415	23
NGC7418	Gx	Gru	22 56.6	-37 02	1423,1424	384, 385	23
NGC7421	Gx	Gru	22 56.1	-37 21	1423,1424	384, 385	23
NGC7424	Gx	Gru	22 57.3	-41 04	1445	415	23
NGC7448	Gx	Peg	23 00.1	+15 59	1209,1210	213	17
NGC 7454	Gx	Peg	23 01.1	+16 23	1209,1210	168,213	17
4sl = Asterism; BN = Bright Nebulo; CGx = Cl = Open Cluster; PN = Plonefory Nebulo; *			usler of Galaxies; DN = Dark Nebulo; GC = Globular Cluster; Gx = C = Star; * * = Double/Multiple Star; Var = Variable Star				ioloxy;

MAY

The Grandeur of Omega Centauri