Globular cluster Messier 2 (M2, NGC 7089) was discovered by Maraldi on September 11, 1746. Charles Messier independently rediscovered and cataloged it exactly 14 years later, on September 11, 1760, as a "nebula without stars." William Herschel was the first to resolve it into stars.

As most globular clusters, M2's central part is pretty compressed: The dense central core of globular cluster M2 is only 0.34 arc minutes or about 20 arc seconds in diameter, corresponding to a diameter of 3.7 light years. Its half-mass radius is 0.93 arc minutes (56 arc seconds, or 10 light years linearly). On the other hand, its tidal radius is large: 21.45 minutes of arc, corresponding to a radius of 233 light years beyond which member stars would escape because of tidal gravitational forces from the Milky Way Galaxy.

M2's brightest stars are red and yellow giants of magnitude 13.1, while its horizontal branch stars have an apparent brightness of 16.1. The cluster's overall spectral type has been given with F0, its color index as -0.06; modern values are spectral type F4, B-V = 0.66.

I shot this using the amazing facilities located at the Sierra Stars Observatory. You can find out about the services provided by them at www.sierrastars.com.