John Herschel discovered NGC 2991 = h634 on 24 Feb 1827 (sweep 59) and recorded "F; vS; bM. The s p of two [with NGC 2994]." His position is less than 30" north of the center of UGC 5233, though he missed NGC 2988 (found in 1855 with the 72"), which is attached on the west side.

400/500mm - 17.5" (4/15/93): fairly faint, small, slightly elongated 4:3 NW-SE, even concentration to a small bright core. A mag 12.5 star is 1.1' SSE. Forms a contact pair with NGC 2988 (discovered by Rosse) just off the west edge. NGC 2994 lies 7.5' NE.

600/800mm - 24" (4/13/18): at 375x fairly faint, fairly small, sharply concentrated with a very small bright core and stellar nucleus. The halo is a fairly low surface brightness and ~45" diameter. A mag 13 star is 1.0' SSE. NGC 2988 appears as a small "spike" attached to the west side and extending to the southwest. NGC 2994 lies 7.6' NE, forming a physical triplet (USGC U259)

Notes by Steve Gottlieb