John Herschel discovered NGC 3974 = h1021, along with NGC 3964, on 9 Mar 1828 and recorded "vF; S; R; bM; 15". The f of 2."

400/500mm - 17.5" (5/11/96): faint, fairly small, irregularly round, 1.0' diameter, weak concentration. A mag 14 star is 1.4' preceding. Fainter of pair with NGC 3970 3.6' SW. Located 20' WNW of mag 7 SAO 157002.

Notes by Steve Gottlieb