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 June 2nd and morning of the 3rd, 2009.

CAMERA:  Canon XSI, 450D

TELESCOPE:  Orion 100mm ED refractor @ F/18

ISO SETTING:  800

EXPOSURES:  40

EXPOSURE LENGTH:  5min.

TOTAL EXPOSURE LENGTH:  3hrs, 20min.

SUBTRACTIONS:  20 dark frames and 10 bias frames.

CAPTURE SOFTWARE:  MaximDL

STACKING SOFTWARE:  Deep Sky Stacker

PROCESSING:  Photoshop CS3