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Catalogue and alternative designations M5, NGC 5904


Type Globular Cluster 
Position 15 18 33, 02 04 52
Constellation Serpens
Camera and Telescope STXL16200 and 36.8 cm Ritchey Chretien
Focal Ratio F9
Exposure Details A LRGB image with Luminance unbinned and colours binned 2x2.  The exposure times were Luminance = 110 minutes, Red = 70 minutes, Green = Blue = 60 minutes.
Description M5 was discovered by Kirch in 1702 and noted by Messier in 1764.  The first person to identify it as a star cluster was Herschel in 1791. At magnitude 5.95 it is theoretically just visible to the unaided eye.  It's one of the largest globulars known with an apparent diameter of 23' and an actual diameter of 165 light years. The distance is about 24,500 light years.