William Herschel discovered NGC 3902 = H III-321 = h989 on 6 Apr 1785 (sweep 393) and noted "vF, pS." CH's reduction is 10 sec of time preceding UGC 6790. JH made two observations and measured a more accurate RA.

400/500mm - 17.5" (5/4/02): fairly faint, moderately large, elongated 3:2 E-W, 1.2'x0.8', weak concentration. Member of the nearby group LGG 254 and located ~2 degrees NW of the NGC 4005 cluster.

Notes by Steve Gottlieb