M10

From South Dublin Astronomical Society

M10
Type	Globular cluster
NGC	NGC 6254
Constellation	Ophiuchus
Right Ascension	16h 57.1m
Declination	-4° 06’
Magnitude	6.6
Size	20 arc min.
Image:M10 messier image.jpg

Seven Messier globulars are in Ophiuchus — M9, M10, M12, M14, M19, M62, and M107. All are visible in binoculars but the easiest are the nice pairing of M10 and M12 in the torso of the Serpent Bearer. There is no useful bright reference stars nearby to let you quickly spot the two but slowly scan about 10º east of the magnitude 3 pair of Delta (δ) and Epsilon (ε) Ophiuchi (known as Yed Prior and Yed Posterior respectively) and you should spot both globulars looking like fuzzy stars. Although both appear similar in size, M12 is marginally brighter. Spend a little time studying the appearance of each though. Is our estimate of which is brightest correct? A faint pair of stars lies between both and you’ll also see 30 Ophiuchi a little southeast of M10. The closer of the two globulars is M10 which is 14,000 light years away while M12 lies 19,000 light years distant.