William Herschel discovered NGC 3978 = H II-840 = h1023 on 19 Mar 1790 (sweep 953) and noted "F, S, bM." CH's reduced position is 3' south of UGC 6919. JH made two observations and measured an accurate position. Harold Corwin suggests IC 3180 may be a duplicate observation. See his notes on that number.

400/500mm - 17.5" (4/13/91): fairly faint, fairly small, round, broad concentration. Located just 4' W of mag 8.0 SAO 15664 and 7.6' ENE of a mag 9.5 star. A mag 13 star is 1.7' SSE. Forms a pair with NGC 3975 2' WNW.

Notes by Steve Gottlieb