Combination of 15, 1 minute images unfiltered.
SBIG STL-1001E CCD. 20" f/6.8 Dall-Kirkham cassegrain telescope at prime focus.

NGC 2509 is a fairly large cluster in Puppis. Most of the stars are rather faint, with the 3 brightest forming a large, almost equilateral triangle surrounding the cluster. The faint, edge-on spiral galaxy visible on the lower right of the cluster is PGC 79360.