Albert Marth discovered NGC 4432 = m 240 on 22 Mar 1865 with Lassell's 48-inch on Malta and noted "2* in a F nebulosity." His position matches NGC 4432 = UGC 7570, just 2.5' southeast of NGC 4430, though the brighter galaxy is not mentioned.

400/500mm - 17.5" (4/21/90): extremely faint, very small, slightly elongated N-S. A mag 15 star is 0.7' NW of center. Forms a close pair with NGC 4430 2.5' NW.

Notes by Steve Gottlieb