William Herschel discovered NGC 3433 = H III-20 = h783 on 11 Mar 1784 (sweep 164) and noted as "vF, r[esolvable]". There is nothing at his position, but 1 minute of RA east and 2' N is UGC 5981 = PGC 32605. On 18 Jan 1828 (sweep 120), John Hershel recorded "eF; vL; R; vglbM; 2' diam."

400/500mm - 17.5" (2/28/87): moderately bright, moderately large, diffuse, weak concentration, slightly elongated. NGC 3438 lies 25' NNE.

600/800mm - 24" (2/22/14): moderately bright, large, irregularly round, 2.5'x2.0', fairly low surface brightness, weak even concentration to small, slightly bright core and a faint stellar nucleus. Appears to be a face-on spiral, though too faint to resolve the arms. A mag 9.6 star is 8.5' E and 6' further NE of this star is NGC 3444.

Notes by Steve Gottlieb