APRIL

The Intergalactic Wanderer and Some Extragalactic Wonders

Where's the best deep-sky observing in the heavens? Scotty always pointed observers to the area high overhead, where the sky is usually darkest. "Moving our telescopes away from the zenith," he explained, "we begin to look through more atmosphere, dust, and smog that not only dims the view but also reduces contrast and curtails the amount of detail visible in faint, diffuse objects." For those of us who spend most of our time viewing the northern skies, early April evenings might seem to be a lost cause, because that's when Lynx, a rather dull naked-eye celestial gathering, rides high overhead. But Scotty found it to be a repository for galaxies and a host of other deep-sky objects. They are scattered generously across the constellation, and all are within the range of 6- or 8-inch telescopes. Here Scotty investigates the history of the celestial feline and introduces some of its intriguing globular clusters and galaxies.

r enturies of folklore mark April as the month when the world shakes free of

\__winter’s frozen bondage. For some amateurs it is also a time to dust off the

telescope and pay more attention to weather forecasts that predict clear skies. For those of us at northern latitudes, it’s refreshing to step outside into evening temperatures that seem like a heat wave and find winter’s steel-gray cirrus clouds scrubbed from the sky.

High in the evening sky in early April lies one of the great vacant spaces of the celestial vault. Between the cluster-studded sparkling of Auriga and the hordes of galaxies in Ursa Major is a void that was ignored by celestial cartographers until the late 17th century. Then Polish astronomer and instrument maker Johannes Hevelius, unable to resist the temptation of a blank space, filled the area with his constellation Lynx.

Lynx endured the test of time to become one of the 88 constellations officially ^recognized by the International Astronomical Union since 1930. Hevelius created several others, and for those who have an interest in such things, I recommend jeorge Lovis history of celestial cartography that appears as the introduction to ⁰ time 1 of Uranometria 2000.0. Lovi includes a reproduction of an early 19th-eentury American star chart by Elijah H. Burritt. Just below Lynx you’ll find Telescopium Hcrschelii, a short-lived attempt to honor the great British astron omer William Herschel.

According to William H. Smyth, Hevclius defended his creation of Lynx by noting that the space it occupied was one that celestial globe makers usually filled with "Title and Dedication.” If so, then we owe thanks to Hevelius. His original depiction of Lynx had only 19 stars. Over the years the sophistication of cartographers and some tampering with constellation boundaries increased this number. Dalmiro F. Brocchi included 63 stars in Lynx in his American Association of Variable Star Observers Star Atlas, published in 1936.

Brocchi’s charts had a rigorous magnitude limit of 6.05. Since they were intended for star-hopping to faint variable stars, he adjusted the size of his star disks for every tenth of a magnitude. I have seen and used a specially-made drop, bow pen with its adjusting knob calibrated for star magnitudes. It resulted in a chart that looked like the sky. Devoid of bright stars and lacking a decent trace of a geometrical pattern on which to pin some celestial creature, Lynx pays us back with interesting deep-sky objects.

Figure 4.1

Called the Intergalactic Wanderer, NGC 2419 in Lynx is a very remote globular cluster that may be independent of our Milky Way system.

Perhaps the most famous is the globular cluster NGC 2419, located some 7° north of brilliant Castor in Gemini (Figure 4.1). When William Herschel discovered it in December 1788, he called it a bright nebula (his class I of objects) and continued with his survey of the sky. Little could he have imagined that it would bedevil generations of future astronomers.

Lord Rosse, observing with his huge reflectors in Ireland during the mid-1800s, suggested that NGC 2419 was a globular cluster, but not until 1922 was its globular nature established beyond dispute. Although this cluster’s sky location nearly opposite the center of our Milky Way is unusual, what is really of interest

norners is the cluster’s distance. According to Sky Catalogue 2000.0, NGC ^{10 1Sll<}inore than 300,000 light-years from the Sun. Lying nearly twice as far away 2^1 ^Large Magellanic Cloud, the cluster drifts through intergalactic space.Thus, ^{aS I,1L} been referred to as an "intergalactic wanderer.”

'*¹¹³⁵ _nj_{ng t}he distances for globulars listed in Sky Catalogue 2000.0 reveals sev-other very distant objects, but none is even close to the brightness of NGC 19 Of the approximately 100 known globular clusters, almost all lie within a z- 000-light-year radius of the galactic center.

’ pespite its great distance, NGC 2419 shines at about 10th magnitude and _s a little less than 2' across. Under good observing conditions the cluster should be visible with a 3-inch telescope. I once saw it from Kansas with a 4-inch refractor stopped to 2 inches and lOOx.The cluster should always be within reach of a 6-inch glass, and a 12-inch may start to show some hint of individual stars around its edge. It is a beautiful object for a 17-inch. More distant globular clusters have been discovered on photographs made with the 48-inch Schmidt telescope on Palomar Mountain. However, it is unlikely that any would be within the visual reach of amateur instruments.

Host of Galaxies

Burnham’s Celestial Handbook lists 13 galaxies in Lynx, but most are faint. One exception is NGC 2683, a nearly edge-on spiral with a visual magnitude of about 9.3. Under good sky conditions, this galaxy can be seen with moderate-sized binoculars firmly held on a tripod. Its distinctive cigar shape can even be picked up while sweeping. In general, a loss of 1.5 or 2 magnitudes occurs when a rigid stand is not used. I was amazed at how much better my 20-power Apogee telescope performed after a solid support was made for it. Experienced observers know that bright objects can be seen during a sweep, while those near the telescope’s magnitude limit require the field of view to be steady. It helps to know exactly where to look. In this way I was able to locate NGC 2683 with a 3-inch aperture at 60x.The galaxy is also a pleasant sight in a 10-inch at 120x. NGC 2683 was aptly termed by Leland S. Copeland “the forerunner of the galactic host of the spring and early summer.” Curiously, it is not mentioned by W. H. Smyth or Thomas Webb in their guides. Yet it is an easy object for a 4-inch telescope on just about any night.

Three galaxies form a nice little triangle, with 3rd-magnitude Alpha (a) Lyncis ^at *^{ls ce}nter (Figure 4.2), and arc plotted in Wil Tirion’s Sky Atlas 2000.0. They are fine for beginning observers, because the bright star serves as a good point to start ^SWeeping, and the galaxies are never more than one or two low-power diameters ^away. Tiny NGC 2832 lies 7j° southwest of Alpha. I first viewed this 13th-magni-galaxy in 1932 with the 6-inch Clark refractor at Washburn Observatory in h ^IScons>n. This was the same telescope that astronomer Sherburne W. Burnham used around the turn of the century to discover many double stars. Try searching for it with lOOx, as this round patch, only 0.6' in diameter, may be missed at _r°^^{Cr m}agnifications. Robert Schmidt in Nebraska found NGC 2832 with a 6-inch ^ctor at 80x, but he was unable to glimpse its companion galaxy, NGC 2831, located just 48" southwest and a magnitude fainter. How small an aperture win show this companion galaxy?

A much easier object is the 10.7-magnitude spiral NGC 2859. the largest and brightest of the three galaxies plotted around Alpha. It, too, is only V<° f_rort)

Alpha Lyncis, but to the east. It is easy to locate. Center your telescope on Alpha Lyncis and wait about 37: minutes with the drive not operating. The galaxy should then be just north of center in the eyepiece’s field of view. You should be able to see NGC 2859 with a 4-inch aperture. Try keeping Alpha out of the field, as its glare may hinder your ability to find the galaxy’s slightly oval disk measuring roughly 4' across. Some observers mention seeing a bright core surrounded by a faint outer ring, which is consistent with the galaxy’s barred spiral form on photographs. Arizona observer Ron Morales found the object with an 8-inch f/5 reflector at 60x, and he reports using averted vision to see the outer ring. When W. H. Smyth published his famous Cycle of Celestial Objects in 1844, this was the only nebula he listed for the constellation Lynx. However, with the official reorganization of constellation boundaries in 1930, NGC 2859 became part of Leo Minor.

The third spiral galaxy is NGC 2793, which is slightly less than 1° west of Alpha. It is about T in diameter. Since it is small, try sweeping with powers of 70x to lOOx. For observers with very good skies, a 10-inch or larger telescope, or unbounded confidence, should show NGC 2793. In my 10-inch reflector it appeared about magnitude 12.6, with a featureless disk a little less than T in diameter.

In northern Lynx there are five more interesting galaxies which are all about 12th magnitude. Perhaps the easiest is NGC 2500. Its oval outline is about 2' in diameter. A trifle more difficult is circular NGC 2537, which looks like a faint planetary nebula T in diameter. When searching for this tiny object, use at least 70x to avoid missing it. The faintest galaxy in the collection is 12.5-magnitude NGC 2541. It is roughly 5' long and about half as wide. NGC 2549 is listed as pho-uj_c magnitude 12.2. Visually 1 make it 11.8, and have glimpsed it with my mgr*’! _refractor. In a 10-inch reflector its 1.8'-long spindle shape is unmis-⁴ 'ⁿ\ ■ Our final galaxy of the five is NGC 2552. Its roughly circular outline is j_n diameter, and 1 make its visual magnitude to be about 12.3.

^atl°^Ul Cther galaxy in the area is NGC 2782. I found it easy with the 4-inch. and ^A ._(al magnitude 11.9. It is of great interest because it is a Seyfcrt galaxy, a spi-^!ll:’^ith _a compact, energetic core. I estimate it to be I¹// in diameter with a mag-^tude of ¹¹ -⁹-^,n ph°^tog^raP^{lls il} shows a small but especially bright nucleus. The ⁿ’ _se outer spiral arms visible in photographs are reminiscent of M51, the f' ious Whirlpool Galaxy in Canes Venatici.

³ After you look at NGC 2782, let the field drift for 7’A minutes with the drive off. You should then have NGC 2844 nearly centered in the eyepiece. This galaxy has two 7th-niagnitude stars less than 10' to the northcast and northwest which help to locate this 127’-magnitude wisp, only 1.0' x 0.5' in size. Since the position of this galaxy is readily pinpointed, averted vision is very easy to use.

The Dynamic Duo

Circumpolar objects are special because they can be observed all night. But that statement is somewhat misleading. That they do not set from a given location certainly sounds auspicious, but how useful is it to look at a galaxy, say, 5° above the horizon? Unless we're after a temporal event, such as a comet or supernova, a deep-sky object lower than 10° above the horizon is usually an unattractive option for a night's observing. The object is dimmed because we are looking through the densest part of Earth's atmosphere, which often includes a lot of pollution. Usually, it's better to set our sights higher in the sky. "Near the horizon," Scotty says, "an altitude change of only a degree or two can drastically affect the appearance of a celestial sight. But when objects are much higher up, an altitude change of 10° or so is necessary before image quality is appreciably changed." He then points out that of the 110 Messier objects, only about four may be considered circumpolar at latitude 40° north, when an allowance of 10° is made for horizon haze. "Two of these," he says, "M52 and M103, barely fall within 30° of the north pole, but M81 and M82, in Ursa Major, are easily visible every night of the year. This pair of show objects should be familiar to every amateur."

Our telescopes clanked as the car tires bounced over each expansion joint on the narrow approach road to the Golden Gate Bridge. The windshield **P^ers assaulted the accumulation of San Francisco fog, but we could hardly see pavement. Instead we followed tail-lights on the cars ahead of us. It didn’t ^Seem like a very good night for a star party.

oon we were on a long gentle climb up twisting roads when suddenly we broke ^vaul "'        *^ay^er" O^vcrh^ead stars were sprinkled across heaven’s darkened

■ Good, but not great, I thought as I looked back expecting to see a flood of light from the city across the bay. But there was no San Francisco — not even t|_)c faintest trace. It was hidden by the mist blanketing the valley below us. The f_Og also trapped the ground’s heat. No obnoxious thermals rose to wobble our view The air above was locked in elaborate calm, as we soon learned when we point ed our telescopes skyward.

Figure 4.3

The famous dynamic galaxies M81 (bottom) and M82 (top) in Ursa Major.

My first target for the evening was the stunning pair of galaxies M81 and M82 in Ursa Major (Figure 4.3). Both are visible in the same low-power field, and both can be seen in a 2-inch finder. A favorite of mine, M81 is the brightest and most famous of the circumpolar Messier galaxies as seen from 40° north latitude. A beautiful spiral, it lies nearly 70° north of the equator. At such a location altitude changes very slowly with the passage of time. The galaxy is just a little brighter than 7th magnitude, and there are people who can see such stars with the naked eye. Has anyone glimpsed M81 without optical aid? It is certainly easy in even the smallest pair of binoculars.

Sky Catalogue 2000.0, Vol. 2, lists M81’s oval disk as being about 26' long. This implies an object nearly a Moon’s width across, but the catalog measurements include faint extensions of the spiral arms that are not visible in amateur telescopes. Thus, observers will see an object that appears only about half as large. M81’s arms are wound tightly around its large core, and it would appear that

. )ie beyond the range of most amateur telescopes. Indeed, observer Ronald ^I,KSL was only able to trace out one arm visually with a 30-inch telescope at ’s McDonald Observatory. Yet, on those infrequent nights when trans-eV is particularly good, M81's sharply sculptured grace stands luminous in ^able sky. Its edges are crisp, and observers with a 6-inch telescope will see ³ _s of several arms, while 16-inch and larger telescopes can likely pick out one or more of the full spiral arms.

While M81 is a textbook example of a spiral galaxy, its companion, M82, is nything but. It is, in fact, one of the most unusual galaxies within the range of small telescopes. At magnitude 8.4, it is also within the grasp of binoculars. Like its neighbor. M82 was discovered on the last day of 1774 by astronomer Johann Bode at Berlin Observatory. Some older books even refer to the two galaxies as -Bode’s nebulae."

Visually M82 appears as a spindle of light about 10' long and relatively bright. That night under the Golden Gate skies I could not resist pretending that I was looking at the hulk of an ancient space cruiser torn to shreds in some long-forgotten galactic war. Alas, admitting to such fantasies can lead to trouble. In a lecture I once likened M82 to an Egyptian mummy wrapped in ragged linen strips. I then got letters insisting that this proved the Egyptians were immigrants from outer space!

Larger amateur telescopes will show traces of the central mottling clearly recorded in long-exposure photographs, giving M82 the appearance of some brimstone hell where dark filaments jostle with bright fragments of the galaxy. For many years astronomers attributed M82’s turmoiled appearance to an explosion of unparalleled magnitude occurring within the galaxy. During the 1980s, however, a somewhat gentler process of intense star formation peppered with supernovae became recognized as the cause — somewhat like the Orion Nebula on a galactic scale. Regardless of the events behind M82’s appearance, its close proximity to M81 makes a wonderful example of how dissimilar galaxies can look in amateur telescopes.

Several interesting but lesser-known galaxies lie nearby. NGC 2976 is a bit less than I!/,⁰ southwest of M81. It is an easy 10th magnitude and 4' across. I have seen it in a Skyscope reflector as well as a 2.4-inch Unitron refractor. To my eye this spiral has a slight diamond shape. NGC 3077 is an elliptical galaxy similar in size and brightness to NGC 2976. It lies about Va⁰ east-southeast of M81. Not far away lie two 11 th-magnitude galaxies. NGC 2787 is a barred spiral 2' in diameter. A spiral of type Sb is NGC 2985. While the Shapley-Ames Catalog* of galax-*es gives the diameter as 3', I see this object as T in a 4-inch.

By the way, I should mention that M81 took on special significance for me in ^86. Its NGC number, 3031, is shared by an asteroid that was named in my

survey of bright galaxies completed by Harlow Shapley and Adelaide Ames in 1932, this catalog was '^^{< c>r}porated in the Revised Shapley-Ames Catalog of Bright Galaxies by Allan Sandage and Gustav A. ^arr>mann and published by the Carnegie Institution of Washington in 1981. honor. It's a delightful coincidence, prompting me to “adopt" M81: it is a show piece and much easier to see than my asteroid.

Seeing Double, and a Mysterious Planetary in Lynx

When Scotty first began writing his Deep-Sky Wonders column, amateur telescope making was in its prime. To test the optical quality of their handmade marvels, telescope makers often turned them to known double stars to see if they could resolve their components at the Dawes limit — the theroetical minimum separation observable with a telescope of a given aperture. But the Dawes limit is not an ironclad measure of performance. Seeing conditions may well affect double-star detections. One way to minimize any atmospheric effects is to look at doubles in deep twilight when they're high overhead, such as those found in Lynx on cool April evenings.

Lynx,the celestial feline,is perhaps most noteworthy for its fine double stars.

Double stars are frequently a test of observers’ seeing conditions rather than the optical quality of their telescopes. For this reason, I must first mention the difficult double Beta (0) Delphini, which never gets more than 0.7" apart. A flood of mail has arrived from amateurs who split the pair. Typical is the report of Charles Cyrus of Baltimore, Maryland, whose 1272-inch f/7.2 reflector has no clock drive. At 572x he saw the components clearly separated. After placing a 10-inch aperture mask on the telescope he could still make out the pair but this time the images were in contact. An 8-inch mask showed the companion as only a lump in the side of the primary.

In applause of this sighting, I will first describe three very different doubles in Lynx. Even the smallest telescopes will be suitable for 5th-magnitude 19 Lyncis. The primary (almost always the brightest star in a multiple system) is magnitude 5.5, and some 15" to the northwest is the 6.5-magnitude secondary. Because of the much wider separation, many double-star catalogs do not list an llth-mag-nitude star more than T to the west-northwest, but a 3-inch telescope should show the three stars nicely.

Our next double star, 10 Ursae Majoris, is now well within the border of Lynx because of the new constellation boundaries set by the International Astronomical Union in 1930. The two components, of magnitudes 4 and 6, are very close, and I suspect they will require a 10-inch telescope with very good optics and a magnification of 300x. The fainter star completes an orbit of the brighter one every 22 years; in 1981 the companion was 0.7" due north of it.

The double star Burnham 576 presents a different problem for the observer. As the components are separated by 1.5", it would normally be an easy object for a 4-inch telescope. However, the companion is 47’ magnitudes fainter than the 7th-magnitude primary and may easily be lost in the brighter star’s glare. Joe Ashbrook’s discussion of Harold Peterson’s diagram plotting telescope performance on double stars, on page 380 of the November 1980 issue of Sky & _oe will be valuable lo anyone interested in observing close doubles with ^7<-h' large magnitude differences.

^SUQne good technique on such doubles takes advantage of the diffraction spikes d by a telescope's spider (the secondary mirror support). Place the com-^caUS _etween the spikes from the brighter star. Doing this will often help ive the visibility of the fainter companion star. But what about refractors d the popular Schmidt-Cassegrain telescopes, which have no spiders? Here it

• ³ customary to make a hexagonal aperture mask, like the one described on page 407 of the June 1975 issue of Sky & Telescope. I find it even simpler to place a cross of black electrical tape over the front of the objective (or corrector plate) _CCH Be careful not to let the sticky tape actually touch the glass surface. On a

• 4 inch aperture I have used tape 7<- and '/’-inch wide with good results. One-inch-wide tape carefully placed on the spider vanes of my old 10-inch reflector also enhanced the diffraction spikes.

In the early 1930s I placed a cross of '/2-inch-wide tape on the 6-inch Clark refractor that had been used by the great double-star observer S. W. Burnham. At 500x, I was able to split Sirius in the winter and Antares in the summer.

A Planetary Mystery Solved

Lynx has another interesting object in the form of the planetary nebula PK 164+31.1, which is often mistaken for the nearby galaxies NGC 2474 and 2475. The mystery surrounding the confusion was neatly told by Nancy and Ronald Buta on page 368 of the April 1981 issue of Sky & Telescope. In a nutshell it goes like this: Both William Herschel and his son John separately viewed the tiny galaxy NGC 2474. Later a close companion was found by Rosse, and both galaxies were listed in the NGC. So far, so good.

In 1939 two researchers at Harvard Observatory were scanning photographs when they discovered a faint planetary nebula only '/2⁰ north of the galaxies (Figure 4.4). As fate would have it, the planetary had two bright knots on opposite sides of its ringlike structure. The researchers assumed these were the objects seen by the Herschels and Rosse, apparently overlooking the slight difference j_n position. It didn’t take long before catalogs and star charts were a confused mess regarding the positions and proper identifications of these objects.

Today, however, all is well, due in part to the work of Nancy and Ron Buta. Charts in both Sky Atlas 2000.0 and Uranometria 2000.0 show the objects correctly. Sky Catalogue 2000.0 goes as far as saying that the planetary “is not NGC 2474-5.'

Although the planetary has been mentioned several times in this column, I have never received a visual observation of it. From my mail I know that amateur interest in observing planetaries is alive and well. Has anyone looked at PK 164+31.1 with a nebula or O III filter?

About 3° north of the planetary lies a 6th-magnitude star, and just a few arcminutes north of that is a string of faint galaxies running east to west. These may prove a challenge for 16-inch telescopes. They are plotted on the Uranometria 2000.0 charts, but only one, NGC 2469, is listed in Sky Catalogue 2000.0. NGC 2469 is 13th magnitude and about T in diameter. It should be within range of a 10-inch and is a good starting point to look for the others, which are one or two magnitudes fainter.

The Beehive Challenge

Is there a relationship between the clarity of the naked-eye sky and telescopic limiting magnitude? It would seem so, but for one variable — the stability of the atmosphere. For most of us living at or near sea level, transparent nights don't necessarily translate into stable nights in the atmosphere. The leading edge of a cold front, for instance, can push out haze and pollution, making the night sky appear crisp and transparent, but the turbulence associated with the moving front can also cause the stars and planets to "boil." To the naked eye, the night sky looks clear, but through a telescope, the views are a nightmare: stars swell to the apparent size of golf balls and planets appear as if seen through a stream of running water. Scotty introduced one test to tell us what to expect telescopically on clear spring nights. "You'll need only your naked eye to see it," Scotty said. "But if you wear glasses it's best to clean them before heading out under the celestial fires passing quietly overhead."

There are quite a few deep-sky objects near the limit of normal naked-eye vision that serve as guides to atmospheric conditions overhead. One of the oldest and best known involves the Beehive, M44, in Cancer (Figure 4.5). With some experience it is possible to estimate the limiting magnitude of a telescope from a naked-eye view of M44.

For those who have read the Old English heroic poem Beowulf, one of the most stirring passages is the short exaltation to the coming of spring.Translations don’t quite make it. Early northerners had a tough time just surviving the win-

especially during the brutal cold spells that drove the Danes out of Greenland and thereby gave Columbus his later chance at becoming a great his-rical figure. Such harsh conditions left humans with an emotional reaction to *° n° that is all out of proportion to today's general climate. Nevertheless, when the warming does come and the streams and rivers chorus once more, we celebrate in many ways. Amateur astronomers clean their telescopes and start making impossible observing plans.

I’ve always considered the beautiful open star cluster M44, also known as Praescpe, to be symbolic of spring. The ancients knew it as a dimly glowing cloud. If the sky were veiled with the slightest trace of cirrus clouds at the leading edge of a storm system. M44 could not be seen with the naked eye. As early as several centuries B.C., the invisibility of M44 was considered an omen of coming rain. Today amateurs can use the same observation to judge the night sky’s transparency.

The name “Beehive" is apparently of fairly recent origin. To Hipparchus it was the Little Cloud; Aratus called it the Little Mist; and Johann Bayer termed it Nubilum (cloudy sky). Astronomers of the 16th and 17th centuries called it the Nebula, and R. H. Allen (in Star Names: Their Lore and Meaning) says that it was the only universally recognized object that could not be resolved by ordinary vision. Its true nature was first discerned by Galileo, who described it in his 1610 astronomy pamphlet Sidereus Nuncius, as “The nebula called Praesepe, which is not one star only, but a mass of more than 40 small stars. 1 have noticed 30 stars, besides the Aselli.”*

Indeed, only the slightest optical aid is needed to resolve the cluster. In fact, there are 11 stars brighter than magnitude 7.0, which puts them within range of many naked-eye skywatchers. (Remember that the naked-eye limit of 6th mag-

heAselli are two stars — Asellus Borealis (Gamma (y) Cancri) and Asellus Australis (Delta (5) Cancri) — 'ch bracket the Beehive to the north and south, respectively. nitude usually cited in books is an average value. There are well-documented cases of observers seeing fainter than 8.0 without optical aid.)

Although many skilled observers have tried to resolve M44 with the naked eye and failed, there are some notable exceptions. In the early 1980s, Swedish amateur Paul Schlyter wrote me saying that he had seen the cluster as “a patch of light with little bright dots in it” while looking from the cabin window of an aircraft cruising at 37,000 feet. He used a coat over his head to block the aircraft’s interior lights during the observation. I suspect his window was a lot better than most of the ones I’ve looked through on commercial aircraft.

A bit more down to Earth, albeit not quite at sea level, were the observations of Sky & Telescope's Stephen J. O'Meara. He was at the 9,000-foot level of Hawaii’s Mauna Kea when he counted and mapped at least 11 of M44’s stars with the naked eye. He saw more from the mountain’s summit nearly a mile higher, but then he was “aided” by breathing pure oxygen from a tank.

Lest anyone doubt these sightings, consider what the legendary Canadian explorer Thomas James penned in his journal on the night of January 31, 1632, while searching for the Northwest Passage to the Pacific: “There appeared, in the beginning of the night, more Starres in the firmament than ever I had before scene by two thirds. I could see the Cloud in Cancer full of small Starres, and all the [Milky Way] nothing but small Starres; and amongst the Plyades, a great many small Starres.” We can only imagine what the conditions must have been like on that cold winter’s night more than 350 years ago!

I was also interested in James’s comments on the Milky Way. While living in Kansas in the 1950s, I had watched how our galaxy’s naked-eye appearance changes with varying atmospheric transparency. Under average conditions it is a smear of uniform luminosity within which stars to 5th magnitude are sharply defined. With increasing transparency the luminous background becomes very pronounced and tends to drown out 4th-magnitude and fainter stars. (These conditions are probably the best most observers see.) On very rare occasions, however, when the air is extremely clear, the luminous surface vanishes, to be replaced with myriads of 6th- to 8th-magnitude stars. I have seen this spectacle from Kansas and, in the 1930s, from Arizona, but never from my home in Connecticut.

Thus, it seems pretty clear that M44 can be resolved with the unaided eye, but it must take an exceptional night. You might also try viewing M44 through a cardboard tube, blackened on the inside, so interference from stray light will be eliminated and the chance of success improved. If any individual stars are seen, their locations relative to more conspicuous objects should be sketched. It would be a worthwhile project for someone to record the times when M44 is and is not visible to the naked eye, and at the same time the faintest star that is seen nearby. A series of such observations would allow a threshold magnitude to be determined for the cluster’s visibility.

In low-power fields, finders, and binoculars, M44 is a brilliant show object. H has no sharp boundary. No one can say for sure where the cluster’s faint glow merges into the placid sky background. And the center is hardly brighter than

There’s no trace of nebulosity here, though current astronomical theory tells

us that there must have been material mixed with the stars when they were born

some 650 million years ago. M44 is one of the closest open clusters, at a distance of only about 500 light-years. Some 200 stars of between 6th and 14th magnitude are believed to be true members of the group, and over 350 stars to as faint as 17th magnitude have been listed in its vicinity. The average distance between M44's stars is rather large, and thus the group would normally be quite susceptible to the galactic forces that break up all open clusters. However, this process is probably slowed by the fact that M44 is located well outside the galactic plane.

Contrasting with the modest age of M44 (fish were already swimming in Earth’s oceans when it formed) is that of M67. Studies indicate that this open cluster (Figure 4.6) is not much younger than the solar system, having been born perhaps 3.2 billion years ago. As far as open clusters go, only NGC 188 in Cepheus is known to be older. When conditions are right, M67 can be seen with the naked eye in the barren sky of Cancer about 8° south of M44. Its apparent diameter is roughly the same as the Moon's, and I estimate its total light to equal that of a 5.9-magnitudc star. The brighter stars in this aged cluster have evolved to the red-giant stage. W. H. Smyth suggested that M67 showed the form of a Phrygian cap (somewhat like a "liberty cap”). The French astronomer Camille Flammarion likened the cluster to a sheaf of corn. What is your opinion?

Galaxies Near M44

Owners of large telescopes, which cannot fit all of M44 into a single field should not bypass the cluster. The New General Catalogue and its two supplemental Index Catalogues list at least eight galaxies here that should be within the grasp of a 12-inch instrument. Brian Skiff called to my attention the two brightest members of this group, NGC 2672 and 2673. NGC 2672 is the brighter (visual magnitude 11.6) and larger of the pair and lies about 2° east-southeast of M44.

Figure 4.7

The close pair

NGC 2672 and NGC 2673 are elliptical galaxies about 2° east-southeast of M44.

NGC 2673, just 'N east of its companion, is slightly more difficult to see at magnitude 12.9 (Figure 4.7). It should be visible easily in a 10-inch telescope at about 150x and a fair test in most skies for anything under 8 inches. One exceptional night I was able to fish it up with the 4-inch Clark at 125x, obtained with a 25-mm eyepiece and a Barlow.

A few degrees eastward are two more galaxies that are plotted in Sky Atlas 2000.0 but have never been mentioned in this column. At magnitude 13.2, NGC 2749 is the more difficult of the pair, but under good skies a 4-inch should reveal its tiny oval disk less than T across; an 8-inch will almost always uncover it. NGC 2764 is a bit larger and brighter. A 4-inch should easily show its disk, which I estimate to be 11th magnitude.

The remaining galaxies are too faint for the Clark and may even challenge those who observe with 17-inchers. NGC 2667A was discovered by d'Arrest with an 11-inch refractor at Copenhagen. The Revised New General Catalogue of ^_(nl<llellar Astronomical Objects (RNGC) lists it as 15th magnitude, but I have lways held the faint magnitudes in the RNGC somewhat suspect. It also rates the onipi’^nion' NGC 2667B, as magnitude 15.5. Rounding out the group is another [^th-magnitude smudge of light. NGC 2677. Have any amateurs seen these?

If you're really into challenges and have access to a 16-inch telescope, try -earching the area about 5° due west of M44. The region is peppered with faint ataxies. I thumbed through Roger W. Sinnott's NGC 2000.0 catalog and tallied _up more than 60 within a 3° window centered on the coordinates 8^h 20^m, +20°. It’s almost a celestial gridlock, with dozens of galaxies scattered like confetti. Just identifying what you find will be a monumental task, since only a handful of the brighter objects are plotted on the Uranometria charts. Good hunting!

Hydra Hysteria

Crossing the meridian on early April evenings, 10° due south of the famous Beehive Cluster, is the familiar naked-eye asterism of six stars forming the head of Hydra. It is the small but conspicuous beginning of the sky's largest constellation. To the naked eye the sinuous constellation does not appear very appealing, just a stretch of dim stars and imagination. But it is rich in deep-sky objects. To Scotty, Hydra was a paradise for the determined galaxy hunter. He needed only to point to the table of Hydra's deep-sky objects in Burnham's Celestial Handbook to explain why. "More than 60 galaxies are listed,'' he said, "but most are fainter than magnitude 12.5 and difficult for 8- or 10-inch telescopes. In a larger instrument these faint galaxies not only are easier to see but often take on individual personalities." So when Scotty went seeking a region of sky that would test the mettle of trained deep-sky observers, something "a little different" from the Messier marathon, Hydra was the perfect place to go mad with desire. Thus was born Scotty's famous celestial voyage, which he coined "Hydra Hysteria."

The idea of a Messier marathon — an all-night session to view as many of the Messier objects as possible — sprung up independently in several locations. According to Harvard Pennington, president of California’s Pomona Valley Amateur Astronomers (PVAA), the first marathon dates to the late 1960s and a group of observers in Spain. On this side of the Atlantic, it was the mid-1970s before amateurs in Florida and Pennsylvania took up the challenge. Unaware of the earlier efforts, California comet hunter Don Machholz suggested a Messier marathon in an article published in the San Jose Amateur Astronomers’ newsletter in 1978. Pennington claims that the cat got out of the bag when I wrote about the Florida and Pennsylvania projects in my March 1979 column. After that, marathons became increasingly popular.

But I began thinking about other voyages across the heavens. I wanted something a little different from the original marathon, something that would sharp-^en the skills needed to star-hop to small and faint galaxies as well as bright and easy objects. Hydra turned out to be the perfect place for such a trek. Indeed, this celestial sea monster stretches across nearly 100° of sky and, with an area of 1,303 square degrees, is the largest of the 88 constellations. (Virgo, with 1,294, is a close second.)

Hydra contains a host of Sth- to 12th-magnitude galaxies. While it is not naked-eye heaven, there is an excellent supply of 5th- to 8th-magnitude stars that are perfect for star-hopping with a finder. I planned my "Hydra Hysteria” using Sky Atlas 2000.0. But another good atlas, especially for the fainter objects is Uranometria 2000.0.

We can begin our hunt at the extreme western edge of Hydra with one of the constellation’s two Messier objects. The open star cluster M48 was long believed to be a "missing” object until Harvard astronomer Owen Gingerich linked it with NGC 2548, which Caroline Herschel discovered in 1783. If Gingerich is correct, the original published position for M48 was about 5° in error. Seemingly, Messier made a mistake of 5° in declination, but his right ascension is correct. But the identification seems pretty certain since there is no other nearby candidate matching Messier’s visual description of M48.

This sparse sprinkling of stars has roughly the angular size of the Moon. Because it is a very loose group, it is best viewed with low magnification or the finder. W. H. Smyth with his 6-inch refractor saw this cluster as “a splendid group, in a rich splashy region of stragglers, which fills the field of view, and has several small pairs, chiefly of the 9th magnitude.” In my big 5-inch binoculars, its shape appears distinctly triangular. This cluster contains about 60 members brighter than 13th magnitude. The total magnitude is about 5.8, and the English author and observer Kenneth Glyn Jones notes that many people can see the cluster’s glow with the naked eye. Being so bright and large, it would seem that M48 would be easy to find. Experience suggests otherwise. The cluster is sparse and the background rich. I’ve never been convinced that it is visible to the naked eye, but it does show nicely in small telescopes.

A prominent group of three stars, including 1 and 2 Hydrae, lies about 3° northeast of M48. Sweeping another 3'11° east of the trio brings us to the spiral galaxy NGC 2642. Although 1 have never mentioned it in this column before. I swept it up with my 4-inch Clark refractor at 120x and estimated its 2' disk to be a little brighter than 12th magnitude. The spiral galaxy NGC 2713 is nearly the same magnitude. It lies 8° north-northeast of NGC 2642, near the stars forming Hydra’s head.

NGC 2962 is a 12th-magnitude spiral almost on the Hydra/Sextans border less than 1° northeast of 2 Sextantis. This galaxy is incorrectly labeled NGC 2967 on the first (1981) printing of Sky Atlas 2000.0, but that was corrected along with nearby NGC 2967 (originally labeled NGC 3067) in later printings. I have seen NGC 2962 easily with a 4-inch rich-field reflector.

We can take a break from observing galaxies by swinging our telescopes southwestward to where the constellations Hydra, Puppis, and Pyxis intersect. There we will find the planetary nebula NGC 2610. It appears about as large as the pla^net Jupiter, but is only 13th magnitude. In the early 1970s I mentioned that I had ^{ncvcr sccn} NGC 2610 in a telescope smaller than 16 inches. This brought a lot of mail, and I can now tell you that under dark, transparent skies I have viewed it with apertures as small as 6 inches. A 10-inch telescope is probably needed for a comfortable view of this tiny but distinct object. My old observing notes made while using a 10-inch reflector do mention NGC 2610, but I may have never searched for it. My records describe collecting it with a 16-inch reflector, and it appeared very bright with the 20-inch Clark refractor at Wesleyan University in Connecticut. Ron Morales, observing from Arizona’s Empire Mountains, had no trouble seeing NGC 2610 with a 10-inch f/5.6 reflector and 16-mm eyepiece. He also fished up the central star, which some catalogs list as 16th magnitude.

Next on our travels across Hydra is a clump of galaxies that lie within a field approximately 10° in diameter with 2nd-magnitude Alpha (a) Hydrae (Alphard) at its northernmost edge. NGC 2763 is the westernmost of the group. It’s a 12th-magnitude spiral about 2' across that should be easy in a 6-inch telescope at lOOx.

NGC 2781 is a little brighter and appears like a thin oval some 3' long. Brighter still is NGC 2811, another spiral galaxy that appears oval in the eyepiece.

NGC 2848 is about 2' across and 12th magnitude. If you can fish it out, try for its 14th-magnitude companion NGC 2851, located 7' to the northeast. It was missed by the Herschels when they made their great visual sky surveys and owes its discovery to the keen eye of Lewis Swift. He picked it up while observing with the 16-inch refractor at Warner Observatory in Rochester, New York, during the 1880s. It’s the hardest object on this month’s list, but I felt that those of you who need a dump truck to get your telescopes to a dark site shouldn’t have it totally easy.

NGC 2855 is easily found about 7z° east-northeast of 26 Hydrae. Its llth-mag-nitude disk is about 2'h' wide and should prove to be a nice target for a 4-inch telescope. Just 172° to its east is NGC 2889,12th magnitude and distinctly rounder.

The galaxy pair NGC 2992-93 is almost as easy to locate since it lies about halfway between 38 and 39 Hydrae. You should have no problem identifying which is which, because NGC 2992 is distinctly cigar-shaped while NGC 2993 is more oval. William Herschel noted them as about the same brightness, but I do not. How do they look to you?

Next comes one of my favorite galaxies, though few other authors ever make much mention of it. NGC 3109 is a long, spindle-shaped, irregular galaxy about half a Moon diameter long. Its ends appear squared off, and while the surface brightness is rather uniform I see a strong hint of curdling with the 4-inch Clark. I m sure NGC 3109 would be a grand sight in a large-aperture telescope.

NGC 3145 lies just a few arcminutes southwest of 4th-magnitude Lambda (^•) Hydrae.The trick here will be to pick it out from the glare of Lambda. High Magnification will certainly help, and the bright star certainly keeps you from getting lost.

NGC 3200 was discovered by William Holden with the 15'A-inch Clark refractor at Washburn Observatory in Madison, Wisconsin. I estimate its oval. 4'-lon« disk to be magnitude 11.1.

If you have a particularly good night, with the sky very clear down to the horizon, you might try for the southern galaxy NGC 2997 in Antlia; it's a little more than 10° southwest of NGC 3200. It’s a small deviation but a great challenge Located about 31° south of the celestial equator, this 11 th-magnitude object is theoretically within reach of every observer in the continental United States. My old observing notes made with a 10-inch reflector in Louisiana during the war years state that NGC 2997 was visible at 40x. I now wish I had tried a higher power, because the record does not comment on any detail being seen.

Now, as we work our way to the eastern end of Hydra, we come to the beautiful globular cluster M68. It was discovered by Pierre Mechain in 1780 and described by Messier as a “nebula without stars.” It took the larger telescopes of William Herschel to resolve M68 into a cluster.Today, the individual stars should be easily visible in a 6-inch telescope. M68, about 4' in diameter, is located below the “sail” of Corvus. You may have to wait until late evening before this object is well above the southern-horizon haze. Only 45' southwest is a 5/2-magnitude star, making this cluster easy to identify. Its total magnitude is 8.2, putting it within reach of 7 x 50 binoculars under favorable conditions. In my 4-inch Clark refractor M68 appears distinctly oval, with tattered streamers winding out from a central disk. The late John Mallas, who did so much to popularize observing the Messier objects, called this cluster a beauty, with a bright central region fading outward to a ragged edge. Older writers have also commented on the peculiar shape of M68, W. H. Smyth likening it to a bishop’s miter, Flammarion to a sheaf of wheat. The Mallas description fits what most amateurs see. About 5' northwest of the globular cluster but not associated with it is the Mira-type variable FI Hydrae, which has a period of 324 days. This red star can become as bright as visual magnitude 9.

NGC 5085 is an 11 th-magnitude spiral galaxy about 3' in diameter. It lies I¹/? south-southeast of 3rd-magnitude Gamma (y) Hydrae. NGC 5101 is a big but faintish spiral about 5' in diameter. I estimate it to shine with the total light of a 10.9-magnitude star, but the surface brightness is low because of its large size.

NGC 5150 is an elliptical galaxy only about 1' across and 13th magnitude. The Uranometria 2000.0 charts show it to be one member of a faint trio, but I have not included the other two because, at 14th magnitude, they are too faint for the Hysteria.

This brings us to the last galaxy on the list, M83. This fine galaxy went undiscovered until the French astronomer Nicolas-Louis de Lacaille sailed south to study the heavens from the Cape of Good Hope in 1751-52. Messier heard of the galaxy’s discovery 30 years later, and he set out to find it in the polluted skies of Paris. Despite the poor atmospheric conditions, he glimpsed the galaxy enough times to add it to his celebrated catalog. The object barely climbed more than 10° above his Paris horizon. It was such a difficult object for him that even the faint ill u-

• _atioD from h*^s telescope's micrometer wires overpowered the galaxy's image. ^Several years ago while in Central America. I saw M83 as a beautiful object in a nch rich-field reflector with a magnification of 20x. This is clearly a delightful iral for ^sma^ telescopes. Its 8th-magnitudc disk is 10' in diameter and seen ncar-^S^face on. Amateur photographs reveal its spiral structure, but visually only a trace 'f this can be seen in a 5-inch Apogee telescope at 20x. A 10-inch reflector in Kansas showed portions of the arms. I've never looked with binoculars for M83, but • _would be worth a try on a good night. In the Messier Album. John Mallas’s draw-j_no made using a 4-inch refractor, suggests that a surprising amount of detail can be seen in M83's inner core by a skilled observer working with a small telescope.

That Messier saw M83 at all should encourage users of large binoculars and small telescopes, especially those who live in more southerly latitudes. On a clear dark night, averted vision and patience will enable nearly all of M83 to be seen in a 10-inch or larger telescope. However, at low power one can sweep past this galaxy, since its bright core is easily mistaken for a star. Messier’s catalog lists seven objects at more southerly declinations than M83. Four were discovered by other observers, but Messier found the remaining three from Paris — quite a feat for his small telescopes. His record was the globular cluster M70 at declination -32° 30' (1780 coordinates). Messier, of course, knew that the southern heavens had their share of deep-sky splendors. We can only speculate that his inner soul yearned to get there somehow and reap more immortality. Yet had he spent a couple of years at the Cape, imagine how many comets his rivals at home would have been able to “steal'’ from him.

Several degrees south of M83 is another interesting galaxy, NGC 5253 in Centaurus. There is some question as to whether this is an irregular or elliptical galaxy, for it would be considered an unusual object in either class. A 6-inch telescope will show it as an evenly illuminated oval some 4' by 2'. Apart from the famous 1885 supernova in the Andromeda Galaxy, which may have reached magnitude 5.4, NGC 5253 has produced the brightest extragalactic stellar outburst on record. A photograph taken on July 8,1895, recorded a 7.2-magnitude supernova very near the center of NGC 5253. Another such event occurred in the same galaxy in 1972, and, although first seen at magnitude 8.5 after maximum light, this star may have also been as bright as magnitude 7.2.

Our final object is the globular cluster NGC 5694. With a diameter of more than 3' and shining at 10th magnitude, it should be relatively easy to find. This is surprising since it is one of the more distant globulars listed in Sky Catalogue 2000.0, which places it some 100,000 light-years from the Sun. Good luck with Your Hydra Hysteria.

Ghost of Jupiter

*ⁿ the summer of 1980 Scotty had cataract surgery on his right eye, which removed ultraviolet-absorbing lens and replaced it with a plastic insert that transmits ultraviolet light. Some feared Scotty's observing was nearing an end. But such fear was unfounded, for Scotty returned to the eyepiece with literally a new outlook on the heavens. His surgery made him eager to test the effectiveness of his new eye lens, for he knew that as we age, the eye's lens begins to yellow and acts as a filter blocking light from the blue end of the spectrum. "Generally, younger observers s_ee planetaries as blue," he said, "while the older ones find them more green." So, in a sense, Scotty, after surgery, was reborn. His views of planetary nebulae and their hot blue central stars proved that his right eye with its artificial lens was receiving more ultraviolet radiation than his natural left eye.

There is a fine planetary nebula in Hydra, NGC 3242. It was discovered in the western half of this sprawling constellation by William Herschel in 1785. It is located about 2° south and slightly west of 4th-magnitude Mu (p) Hydrae. W. H. Smyth mentioned that NGC 3242 is similar in size and color to the planet Jupiter. Accordingly, it still is sometimes called the Ghost of Jupiter (Figure 4.8). “Whatever be its nature,” wrote Smyth, it “must be of awfully enormous magnitude.” Today we know that it is indeed large, by some estimates, about half a light-year across.

Figure 4.8

The planetary nebula NGC 3242, nicknamed the Ghost of Jupiter, is one of the sky's most famous nonMessier objects.

Oddly enough, Smyth, who was a great one for writing about the apparent color of celestial objects, especially double stars, calls this planetary “pale greyish-white.” Many modern observers see it as a striking blue. Indeed, at the Cape of Good Hope John Herschel inspected this planetary several times between 1834 and 1837 with his 18'/4-inch reflector. His notes include: “Colour a decided blue; at all events a good sky-blue. Elliptical; position angle of axis 140° . • 30 long, 25" wide; uniform and very bright; but not quite sharp at the edges.”

The total light of NGC 3242 roughly equals that of an 8th-magnitude star. With a disk only 0.5' in diameter, the surface brightness of this planetary is quite high, averaging about 10 times greater than the Ring Nebula in Lyra. NGC 3242

-liglTtly oval. While the central star is said to be of photographic magnitude ^l!> ₄ i_s much fainter visually. Using a 14!4-inch reflector, California amateur ¹ L-iio Nakamoto estimated the star as magnitude 12.5. (To increase the contrast ¹ -cen the nebula and central star, use as high a magnification as seeing con-

?_ins permit.) Nakamoto also noted the suggestion of two rings. And indeed, _e were very apparent with the 30-inch reflector at the amateur-operated Stony Ri<Je^e Observatory near Mount Wilson.

What does the planetary look like in smaller telescopes? In their Revue des _Coivuellutions. R. Sagot and J. Texereau cite observations by four French amateurs using a variety of instruments: "Easily visible, starlike in a 27-mm 13x find-•_r Readily recognized as a planetary of appreciable size and with shaded edges in a 55-mm refractor at 50x. Central part uniform and very bright in a 95-mm refractor at 95x. Elliptical in a 200-mm reflector at 200x. Central part grayish, and squared into a bright lozenge with a dimming outer edge, in a 215-mm reflector at 375x. Color bluish or yellow.”

Ron Morales found NGC 3242 easily with a 6-inch f/5 telescope at 50x. Recently I looked at it with my 5-inch Apogee telescope and a 20x eyepiece. It appeared slightly oval but without the pointed ends so prominent in photographs of the object. The central star was easily seen with my eye that had its lens removed during cataract surgery. The star appeared almost as bright as the entire planetary in this eye, while it was hardly visible at all in my normal eye. This was surely due to a greater amount of ultraviolet (UV) light reaching the retina of the eye without its natural lens. Central stars in planetaries are generally strong emitters of UV.

1 also examined NGC 3242 with a Lumicon UHC nebula filter. The results were impressive. 1 did not, however, attach the filter to the eyepiece, but rather slipped it in and out of the light beam between my eye and the eyepiece. I learned this method from Mike Mattei of the Amateur Telescope Makers of Boston. Because the eye responds more strongly to a changing image than to a static one, more detail is apparent when the filter is flipped in and out of view than if the scene is held steadily either with or without the filter. Others who have tried this "flicker” method with a filter all report superior results compared with when the filter remains fixed.

One final note about the color of planetaries. The aging of the eye might not be the only factor that determines what color an observer sees. On several occasions I have mentioned that different people see the same planetary as having different colors. So other factors must also affect the color of planetaries. Bruce Chapin of New York City, for example, wrote saying that NGC 7662 in Andromeda at first appeared green in his Celestron 8, but after continued gaz-^lng it turned blue. Such is the mystery with these ghostly glows.

760, 784

+33 25

+02 55

-14 49

+18 19

-15 30

+21 27

-26 09

538, 549,

NGC3109

10 03.1

APRIL OBJECTS (CONTINUED)

Ast = Asterism; BN = Bright Nebulo; CGx = Cluster of Goloxies; DN = Dork Nebulo; GC - Globular Cluster; Gx = Galaxy; OC = Open Cluster; PN = Plonefory Nebulo; * = Star; *» = Double/Multiple Stor; Vor = Variable Sfor