M13 is one of the most beautiful globular clusters in the night sky, comprising some 300,000 stars. Lying in Hercules, at 25,000 ly from Earth, it was first spotted by Edmund Halley (1714) and latter cataloged in 1764 by Charles Messier.
Under dark skies it can be seen with no telescopic aid, since it shines at a 5.8 apparent magnitude.
FS102NSV @f/8 + ST2000 XM