M57, also designated NGC 6720, or most commonly called the "Ring Nebula," is one of the most prominent examples of deep sky objects called planetary nebula.  M57 lies about 2,300 light-years from Earth in the constellation Lyra, and has a visual magnitude of 8.8.

http://en.wikipedia.org/wiki/Ring_Nebula

ABOUT THE IMAGE

DATE/TIME:  The evening of May 20th and morning of the 21st, 2008

CAMERA:  Meade DSI Pro II

TELESCOPE:  Celestron 235mm SCT @ F/10

EXPOSURES:  196

EXPOSURE LENGTH:  15sec.

TOTAL EXPOSURE LENGTH:  49min.

CAPTURE SOFTWARE:  Autostar Suite

STACKING SOFTWARE: Autostar Suite

PROCESSING:  Photoshop CS3