M22

From South Dublin Astronomical Society

M22
Type	Globular cluster
NGC	NGC 6656
Constellation	Sagittarius
Right Ascension	18h 36.4m
Declination	-23° 54’
Magnitude	5.1
Size	32 arc min.
Image:M22 messier image.jpg

The premiere globular cluster of Sagittarius has to be M22. It’s a magnificent object but few people have seen it from our latitude — maybe there is a suspicion it is just too low in the sky. Nothing could be further from the truth and once you see this huge starry globe you’ll wonder aloud about whether M13 deserves the title of best globular in the Northern Hemisphere. It’s an interesting point as each has their merits for visual observers. M22 certainly has a greater apparent diameter than the Hercules cluster. It also appears uniformly bright across it’s extent, appearing as a smudged out greyish glow. There is no obvious central condensation either and larger glasses will easily reveal it distinctly oblate in shape due to the rapid rotation of the cluster. Keep Lambda Sagittarii (Kaus Borealis) at the bottom right edge of your binocular field and you should see M22 about 2½º to the northeast.