Messier 4 or M4 (also designated NGC 6121) is a globular cluster in the constellation of Scorpius. It was discovered by Philippe Loys de Chéseaux in 1746 and catalogued by Charles Messier in 1764. It was the first globular cluster in which individual stars were resolved.

http://en.wikipedia.org/wiki/Messier_4

 

ABOUT THE IMAGE

DATE/TIME:  The evening of June 2nd, 2011.

CAMERA:  Canon XSI, 450Dm

TELESCOPE:  Orion 100mm ED refractor @ F/9

ISO SETTING:  800

EXPOSURES:  23

EXPOSURE LENGTH:  200sec.

TOTAL EXPOSURE LENGTH:  1hr. 16min. 40sec.

SUBTRACTIONS:  10 darkframes, 10 bias frames

CAPTURE SOFTWARE:  MaximDL

STACKING SOFTWARE:  Deep Sky Stacker

PROCESSING:  Photoshop CS3