William Herschel discovered NGC 3870 = H III-833 = h972 on 17 Mar 1790 (sweep 946) and noted "vF, vS." JH made three observations and and measured an accurate position.

400/500mm - 18" (5/31/03): fairly faint, fairly small, slightly elongated SSW-NNE, 0.7'x0.5', weak concentration. Situated near the intersection of a string of stars to the SE and a couple of stars nearly collinear to the ENE. Member of the NGC 3992 (M109) group = LGG 258.

Notes by Steve Gottlieb