William Herschel discovered NGC 2509 = H VIII-1 on 3 Dec 1783 (very early sweep, internal discovery #7) and recorded "a cl of coarsely scattered stars. The place is that of the most comp part, which is not M[iddle]" On 4 Mar 1790 (sweep 934) and logged "a considerably compressed and very rich cl of small star, irr F." and on 15 Mar 1801 (sweep 1095) he noted "a beautiful cl of stars, arranced in a circular order."

400/500mm - 17.5" (3/12/94): 50 stars resolved in a 6'x5' region outlined by a perfect parallelogram. The majority of the stars, though, lie in a prominent dense clump along the NW side of the parallelogram and includes a nice double star. The NE vertex of the parallelogram is a double star with components mag 13/13.5 at 12". The parallelogram has no concentration and the interior southern portion has only a couple of faint stars. Mag 8.6 SAO 153720 lies roughly 6' SE and a bright wide double star consisting of a mag 10.5/12 pair at 26" is 4' NNE of the parallelogram.

Notes by Steve Gottlieb