William Herschel discovered NGC 4431 = H II-171 = h1268 on 17 Apr 1784 (sweep 199) and recorded "Three F nebulae; the two first vS [NGC 4431 and 4436], the third [NGC 4440] S." His single position is roughly 30 sec of RA too large, but the identifications are certain. JH noted "vF; oval gbM; 50"."

300/350mm - 13.1" (5/14/83): faint, very diffuse, slightly elongated. This galaxy is slightly brighter and larger than NGC 4436 4.0' ENE. NGC 4440 lies 6.5' E.

600/800mm - 24" (5/29/14): fairly faint to moderately bright fairly small, elongated 3:2 N-S, 40"x25", broad concentration with a slightly brighter core. A mag 14.4 star is 1.2' E. First of three with fainter NGC 4436 3.8' NE and brighter NGC 4440 6.4' E.

Notes by Steve Gottlieb