M3 was discovered on May 3, 1764, the first object to be discovered by Charles Messier himself. Since then, it has become one of the best-studied globular clusters due to an unusually large number of variable stars (274 so far!)

M3 is one of the largest and brightest clusters in the Milky Way and is made up of around 500,000 stars. Estimated to be about 11.4 billion years old, it is located in the constellation Canes Venatici and lies about 32,600 light years from earth.

Also seen in this image is galaxy NGC 5263 (top; magnitude 14, about 196Mly distant) and NGC 5272 78 (upper right), a high proper-motion star around 543ly away, or roughly 60 times closer to earth than M3.

Telescope:
William Optics Z61; Focal Length: 360mm; Diameter 61mm; f/5.9

Mount:
iOptron CEM26 German equatorial mount (GOTO)

Camera:
ZWO ASI 183C cooled to -10º C;
Optolong UHC filter

10 - 60 second light frames, master dark, master flat
Affinity Photo 2 for stacking and adjustments
Topaz Labs DeNoise AI