This is a series of columns primarily revolving around observing the Messier Catalogue. The intent is to provide the reader a sampling of the Messier objects each month that are most visible in the time frame the column is published. Hence, these deep sky objects should be easily identifiable in and around the month of October. Some months may have a special treat in addition to the Messier Objects. Check the trailer.
M22: Globular Cluster
Without question, M22 should be called “The Great Sagittarius Cluster.” It is a bonfire of 500,000 stars that blazes at magnitude 5.2 and measures 32’ across – about the apparent diameter of the full Moon. Among globulars, it ranks third only to Omega Centauri and 47 Tucanae in brightness and apparent size.
Messier notes: (Observed June 5, 1764) Nebula, below the elliptic, between the head and bow of Sagittarius, close to the seventh-magnitude star Flamsteed 25 Sagittarii. This nebula is circular, does not contain any stars, and is clearly visible in a simple refractor.
NGC note: Very remarkable globular cluster, very bright, very large, round, very rich very much compressed, stars from 11th to 15th magnitude.
Data: Messier 22, AKA: NGC 6656
Con: Sagittarius Mag: 5.2
RA: 18h 36.4m Dec: -23.54
Dist: ~10,400 ly