William Herschel discovered NGC 3891 = H II-723 = h980 on 3 Feb 1788 (sweep 805) and noted "pB, S, lE." JH made three observations, logging "B; R; sbM; 20-30"." on sweep 65, and measured a more accurate position.

400/500mm - 18" (4/5/03): fairly faint, moderately large, oval 3:2 WSW-ENE, 1.0'x0.7'. Contains a very small, brighter core.

Notes by Steve Gottlieb