Asterism in Aquarius

Messier 73 is probably the second least interesting object in Messier's catalog after Messier 40 (the latter is just a dim pair of stars). Charles Messier thought that this group of 4 stars was surrounded by some nebulosity and might be mistaken for a comet, so he included it in his list. Modern research has determined that Messier 73 is not a true cluster (in which the stars are actually close together) but a chance alignment of a few stars (which is called an asterism).

Magnitude 8.9
Apparent Size 1.4'
Distance (light yrs) 2500
Right Ascension 20:58.9
Declination -12 38
Field of View 35' x 27'

Image details:  Exposure times of 5 minutes luminance, and 3 minutes each of red, green and blue, taken with an SBIG ST-8300M camera and a 12" Meade telescope at f/5.6.

December 2011