| Description | This object was discovered by Messier himself (#5 so far) and cataloged on June 1, 1764: "Nebula without star, discovered in the garb which dresses the right arm of Ophiuchus, & situated on the parallel of Zeta of Serpens: this nebula is not large, its light is faint, one can see it nevertheless with an ordinary telescope of three feet and a half [FL]". <--> Ranked 17th in brightness and 14th in size, this is an "average" Messier GC. However, similar to M13, it features a dense, symmetrical, nearly circular core with a ratio I measured of 1.05. Captured toward the end of a long night along with M10 and M12, it looks like conditions, particularly seeing, improved somewhat for this last capture of my evening. I further added a second, wider-field observation from March 2025 captured under better conditions. Brightness falls off fairly dramatically from the center to the edge of the cluster. |
