Édouard Stephan discovered NGC 3784 = St XI-12, along with NGC 3781 and 3785, on 28 Apr 1881. His position matches CGCG 157-006 = PGC 36147.

400/500mm - 17.5" (4/15/93): very faint, fairly small, very elongated 3:1 NW-SE, weak concentration, low surface brightness. Located just 0.9' NE of a mag 10.5 star. Forms a close pair with NGC 3785 0.8' SE with NGC 3781 7' NW.

Notes by Steve Gottlieb