William Denning discovered IC 512 on 23 Aug 1890 with his 10-inch With-Browning reflector while sweeping for comets at 40x. When he determined it was missing from the NGC, he initially thought it was probably a comet, but reobserved it several times on the morning of the 24th without detecting any motion and concluded it was a new nebula. Using 145x, he reported it was "very distinct, round, and a little brighter in the middle. There is a triangle of rather bright telescopic stars on the east side of it."

400/500mm - 17.5" (3/20/93): fairly faint, moderately large, round, almost even surface brightness. A 10' string of stars just east is oriented roughly N-S with a mag 9 star at the north end. Lies 12' W of mag 8.0 SAO 1443.

Notes by Steve Gottlieb