William Herschel discovered NGC 4430 = H II-146 = h1270 on 13 Apr 1784 (sweep 191) and logged "F, pL." He also logged this galaxy just two objects earlier in the sweep, though suspected they were the same object, so assigned a single discovery number. JH noted (sweep 253) "vF; L; R; gbM; 90"." Both missed nearby NGC 4432, which was discovered by Albert Marth.

400/500mm - 17.5" (4/21/90): fairly faint, fairly large, diffuse, elongated 3:2 E-W. There is a sharp light cut-off on the east end. The surface brightness is asymmetric with the brightest portion offset to the east of center with a more extensive faint halo towards the north and west. Forms a close pair with NGC 4432 2.5' SE. Located 8' N of mag 7.9 SAO 119411.

Notes by Steve Gottlieb