The Crescent Nebula (also known as NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light years away.

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

 

ABOUT THE IMAGE

DATE/TIME:  The evening and early morning of July 12th and 13th, 2013.

CAMERA:  Canon XSI, 450Da

TELESCOPE:  Celestron C9.25 SCT @ F/6.3

ISO SETTING:  800

EXPOSURES:  43

EXPOSURE LENGTH:  300sec.

TOTAL EXPOSURE LENGTH:  3hrs., 35min.

SUBTRACTIONS: 16 dark frames, 40 flat frames and 16 dark flat frames.

CAPTURE: MaximDL

STACKING/PRE-PROCESSING: Deep Sky Stacker

PROCESSING: Photoshop CS3