M13, aka The Great Hercules Cluster, is a very compact grouping of more then 100,000 stars, tightly bound together by gravity. The object is believed to have been in existence for at least 14 Billion years, Globular clusters are among the oldest objects in the universe. Hundreds of such objects form a spherical halo around our galaxy. M13 is the brightest such object in the Northern Sky, probably visible to the naked eye as a faint patch of light under ideal conditions. Through the eyepiece of my scope I can make out a bright hazy core surrounded by a tiny sprinkling of stars, larger amateur scopes show significantly more stars (still not like photo, however!)
The object has an apparent diameter of about 15 minutes of arc, about half the size of the full moon. In actuality it is 25,000 Light years away and about 145 Light years in Diameter. In 1974 We actually attempted to send a radio message to any hypothetical inhabitants of the stars surrounding the cluster from the Arecibo Radio Telescope. If the message gets received, expect a reply in about 50,000 years.
Image was built from about 60 30-second subframes through my Televue Genesis Refractor, processed using "DDP" ("Digital Development Process") in AIP4WIN.
Addendum: I originally took this picture in Back and White (Monochrome) over a year ago. A couple of weeks ago I shot some additional frames of the object through color filters (Red, Green, Blue) and combined them with the original to build the color image shown. The actual coloration of the object is quite subtle, it is difficult to determine the accuracy of the colors shown.