Collinder-note

Cr.#

The catalog number assigned by Collinder to each object included in his study.

NGC/Other Cat

Provides connections to the more general resources from which Collinder derived his list of open clusters. Not all of these designations were included in Collinder’s original catalog. They are added here to allow for easier cross referencing with modern resources. In a few cases Collinder got an NGC/IC number wrong, and where the erroneous number might be found in other references, this has been noted. Also, some of his designations, while correct in their time, are seldom used these days. A few of these, such as that for the Coathanger asterism (4-5 Vul)) have been retained as curiosities.

Con

The constellation in which the object is found.

RA and DEC

The celestial coordinates of the objects according to the Historically Corrected New General Catalogue (HCNGC) v1.02. The coordinates listed in Collinder’s dissertation are from the early 1900s and are not reproduced in this checklist. (See original catalog.)

M (v/p)

Estimates of the apparent magnitudes of these clusters, either visual (v) or photographic (p) taken from such sources as NSOG, the SEDS website, and Archinal & Hynes, and The Historically Corrected New General Catalogue (HCNGC) v.1.02. The magnitudes recorded by Collinder often do not agree with modern sources. (See original catalog.)

# Stars

Estimates of the number of stars contained within star clusters, determined by the examination of photographic plates. Most of these counts are by Collinder. Where he did not provide a number one was substituted from other (usually more recent) sources, as indicated by a number in parenthesis. This segregation was done in order to help maintain some sense of what Collinder measured in his work, while still providing useful information to modern observers. Although these numbers can be useful for giving the observer some sense for the cluster’s nature, always bear in mind that the number of stars seen will be strongly influenced by aperture and conditions.

Size ‘

Modern estimates of angular size – in arc minutes – taken from sources such as The Historically Corrected New General Catalogue (HCNGC) v.1.02 and The Night Sky Observer’s Guide (NSOG) by Kepple and Sanner.

Class

A classification system used to describe clusters by comparing them to typical and well known clusters as examples. Classifications of this sort from both Collinder and Lundmark (his doctoral advisor) are included in the original catalog, but only Collinder’s assessment (which in the overwhelming majority of cases is the same as Lundmark’s) are used for this list. This system of descriptive classification is included partly for the historical insight it provides into how these objects were seen by the researcher involved, and also because they might offer an aid to the identification of objects when they are found.

• Plei = Pleiades (M45)
• Praes = Praesepe (M44)
• μ Norm = mu Normae Cluster (NGC 6169)
• Glob = resembled a globular cluster
• Chain = string-like asterism
• Neb = appears nebulous, or contains nebulosity
• nl = none listed
• Notes (n) = Useful information that it is hoped provides some clarification of discrepancies between Collinder’s sources and those currently in use.