Globular cluster M 5 (NGC 5904) in Serpens
The bright globular cluster Messier 5
(NGC 5904) in Serpens, shown from a 15-second yellow-light
(V-band) exposure (in twilight) with a Tektronix 2048x2048 CCD at
the prime focus of the 4-meter Mayall telescope of Kitt Peak
National Observatory. North is at the top and east to the left,
for direct comparison with a chart or eyepiece view.
The image has been block-averaged to 512x512 for this presentation, which uses a logarithmic intensity transformation to preserve information across a wide dynamic range.
The field is 14.3 arcminutes square. This is one of the brighter globular clusters visible from the northern hemisphere, with a listed magnitude of 5.8 (not to be more specific, that's from the Sky Publishing Messier Card).