Johnstone and Bindon Stoney, LdR's assistants, discovered NGC 751 on 11 Oct 1850. It was described as a "D neb [with NGC 750], Pos 171°, Dist 25", nf is a third nebula [NGC 761]."

On 10 Dec 1873, Ralph Copeland gave a more detailed description: "D neb, cB, pL, R, sbM and pF, S, R, sbM." John Herschel's entry for GC 456 is confused; his description "nf h175 NGC 750]" refers to[NGC 761, but he used the same position as NGC 750 ("D neb"), so his comment could be interpreted as referring to NGC 751. Perhaps to avoid confusion, Dreyer added the entry GC 5200 in the GC Supplement (with reference to the 1861 publication) for NGC 751 and used GC 456 for[NGC 761 in the NGC.

200/250mm - 8" (11/28/81): both components of NGC 750/751 merge into a single object.

300/350mm - 13.1" (10/20/84): double nebula with NGC 750 with two distinct nuclei and probably a common halo, oriented N-S.

400/500mm - 17.5" (11/1/86): this is the southern member of double system with NGC 750. Fairly faint, very small, round. Appears smaller and fainter than NGC 750 just off the north edge.

Notes by Steve Gottlieb