William Herschel discovered NGC 4491 = H III-41 = h1304 on 15 Mar 1784 (sweep 174) and noted "vF". CH's reduced position is 4' southeast of UGC 7657. JH logged "pB; L; R; 40"." and measured a fairly accurate position.

400/500mm - 17.5" (4/25/87): fairly faint, elongated NW-SE, fairly small, brighter core. A mag 13.5 star lies 2.2' NE. Forms a pair with NGC 4497 12' NE.

Notes by Steve Gottlieb