γ Comae Berenicis and
The Coma Star Cluster


Gamma Comae Berenicis forms the western tip of the constellation's asterism.

More interestingly gamma Com is in the vicinity (although not apparently a part of) the delicate star cluster simply known as The Coma Star Cluster: binoculars.

The cluster perfectly fills the field of view in binoculars, making it a delightful object of study. Its stars are roughly 275 light years away, one of the closest star clusters.
     About forty stars form the group, the brightest being 12 Comae. Only a half dozen of the stars are fifth-magnitude, the rest being sixth- or even fainter. Altogether they form a dazzling effect in binoculars.


This field of view has three binaries of interest, 12 Comae, 17 Comae, and Struve 1633, all but the later wide binocular doubles.
      12 Com, a multiple system suitable for large binoculars:
           AB: 4.9, 11.8; 57, 36.7"
           AC: 4.9, 8.9; 168, 59"
           AD: 4.9, 10.1; 132, 213.1"
      17 Com: 5.2, 6.6; 250, 145"
      Struve 1633, two equal white stars: 7.0, 7.1; 245, 8.9".

Now moving to the very top of the constellation, two binocular fields northwest, brings you to the very pleasant Struve 1615; the primary is a deep yellow and the companion a much paler yellow, making a subtle contrast: 7.0, 8.6; 87, 26.8".

Retrace your path now back to the Coma Star Cluster, then move one binocular field southwest: 2 Comae is a fine telescopic binary: 6.2, 7.5; 236, 3.7".


The Coma Cluster, for which this constellation is mostly known, (not to confuse this with the Coma Star Cluster) is a rich field of over a thousand galaxies, two binocular fields south of gamma. The galaxies are beyond the measure of binoculars and most telescopes. Ten or so galaxies have apparent magnitudes of 12 to 14, and thus can be seen with medium sized telescopes. But by and large, the subject is far beyond the intention of the current web site.

We will point out, however, the historical importance of the Coma Cluster in astronomy. It was here, while studying the galaxies of the Coma Cluster in 1933, that the brilliant cosmologist Fritz Zwicky came up with the concept of dark matter, an idea that would be igored in astronomical circles for 50 or 60 years.

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1999-2014 by Richard Dibon-Smith.