Back To Constellation of the Month MenuM-4: Lying about 1.5 degrees due west of Antares, this large globular cluster is both easily found, and a treat to observe. It is large, about 15' in diameter and is rather loosely concentrated, letting us resolve its individual stars rather easily. About 8-10 of its brightest members appear to form a bar right through its center, and gives the impression that the cluster is slightly elongated.
M-6: This is a fine open cluster just visible to the naked eye. It is sometimes called the Butterfly Cluster, as some observers see the shape of a flying insectoid amongst its stars. The cluster is large, about 25' in diameter, so use low powers to observe it. Over one hundred stars, many bright or relatively bright can be counted in this area.
M-7: One of the finest open clusters visible in the northern hemisphere, this object is best seen using binoculars or a finderscope. It is large, about 50' in diameter and contains many bright stars loosely concentrated at the center. Telescopic observers are awarded an added treat; at the western edge, but still within the cluster's boundaries, the faint globular cluster NGC 6453 can be seen. How many times have YOU observed M-7 without seeing this ghostly globular?
M-80: This is a small, tightly concentrated globular cluster which is difficult to resolve into its constituent stars, and then only around the edges. It is seen in binoculars as a fuzzy star.
NGC 6231: A fine open cluster, composed of over one hundred stars in a compact 15' area. It actually lies on another spiral arm of our galaxy, closer to the galactic center. According to Burnham's Celestial Handbook, if this cluster was at the same distance from us as the Pleiades, it would appear about the same size as that cluster, but would be about fifty times brighter, with its brightest members shining as bright as Sirius!
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