Édouard Stephan discovered NGC 3864 = St XIII-65 = Sw. I-15, along with NGC 3857, 3859, 3867 and 3868, on 23 Mar 1884. His position matches CGCG 097-130 = PGC 36620. Lewis Swift rediscovered this galaxy on 13 Apr 1885 and reported it in his first discovery list. Swift's position is 8 sec of RA too far west and 1.5' too far south.

400/500mm - 17.5" (3/12/88): very faint, small, round, even surface brightness. Located 3.3' W of NGC 3867 in AGC 1367.

Notes by Steve Gottlieb