William Denning discovered IC 451, along with IC 450, around 1890 with his 10-inch reflector. The discovery was communicated directly to Dreyer as it was not published. The IC positions for both galaxies are 6'-7' too far southeast. Corrected positions were published in the 1937 paper "A study of faint northern galaxies" by Seyfert and Shapley (1937AnHar.105..219S).

600/800mm - 24" (1/28/17): at 375x; fairly faint, fairly small, round, 24" diameter, even surface brightness. Forms a pair with IC 450 4.2' SW.

Notes by Steve Gottlieb