William Herschel discovered NGC 3947 = H II-403 = h1008 on 26 Apr 1785 (sweep 402) and recorded "F, S, irr F." His position is 17 sec too far west. He measured a more accurate position on two later observations, including 27 Dec 1785 (sweep 671). JH recorded "F; mE; bM; a coarse D * precedes."

400/500mm - 17.5" (4/7/89): moderately bright, fairly small, oval E-W. A mag 15.5 star is at the east edge 0.9' from center. Located 3.2' SE of a mag 10 star. Member of the NGC 3937 group with CGCG 127-092 6.0' SSW.

Notes by Steve Gottlieb