Globular Cluster Messier 10
The globular cluster Messier 10 was discovered by Charles Messier on 29th May 1764. He wrote: «Nebula without a star, in the belt of the serpent-bearer, next to the 30th star of this constellation, sixth magnitude after Flamsteed. This nebula is beautiful and round; it was difficult to see with an ordinary telescope of three feet [focal length].» 
M 10 forms an interesting pair with its neighbor Messier 12. According to distance estimates, M 10, at 16'000 to 22'000 light years, is closer than the large globular cluster Messier 13 in the constellation Hercules. The integrated spectral type of M 10 is given as G0. The radial speed of approx. 72 km/s is relatively low compared to other globular clusters. 
|Right Ascension (J2000.0)||16h 57m 08.9s|
|Declination (J2000.0)||-04° 05' 56"|
|Visual magnitude||6.6 mag|
|Metric Distance||4.400 kpc|
|Dreyer Description||! globular, B, vL, R, gvmbM, rrr, st 10…15|
|Identification, Remarks||M 10, GCL 49|
The globular cluster Messier 10 is located in the constellation Serpent Bearer (Ophiuchus) near the 4.82 mag star 30 Ophiuchi. It can best be observed in the months of May to July.
Description pending ...