Messier 55 (also known as M55 or NGC 6809) is a globular cluster in the constellation Sagittarius. It was discovered by Nicolas Louis de Lacaille in 1751 and catalogued by Charles Messier in 1778. M55 is at a distance of about 17,300 light-years away from Earth.

http://en.wikipedia.org/wiki/Messier_55

 

ABOUT THE IMAGE

DATE/TIME:  Evening of August 31st, 2013.

CAMERA:  Canon XSI, 450Da

TELESCOPE:  Celestron C9.25 SCT @ F/6.3

ISO SETTING:  800

EXPOSURES:  17

EXPOSURE LENGTH:  300sec.

TOTAL EXPOSURE LENGTH:  1hr, 25min.

SUBTRACTIONS:  16 darkframes, 40flat frames, 16darkflat frames.

CAPTURE: MaximDL

STACKING/PRE-PROCESSING: Deep Sky Stacker

PROCESSING: Photoshop CS3