Messier 55 - Wikipedia, the free encyclopedia: "Messier 55 (also known as M55 or NGC 6809) is a globular cluster in the constellation Sagittarius. It was discovered by Nicolas Louis de Lacaille in June 16, 1752 while observing from South Africa. Starting in 1754, Charles Messier made several attempts to find this object from Paris, France, but the low declination meant it never rose sufficiently far above the horizon to allow for easy observation. He finally observed and catalogued it in 1778. The cluster can be seen with a pair of 50 mm binoculars, although resolving the individual stars requires a medium-sized telescope."