John Herschel discovered NGC 644 = h2433 (along with brighter NGC 641 = h2432) on 5 Sep 1834 and recorded "F, S, lE, glbM. The following of two [with NGC 641].". His position and description matches ESO 244-043 = PGC 6097.

600/800mm - 24" (10/3/13): difficult due to low elevation (10°) and fairly poor seeing this far south. At 200x appeared very faint, slightly elongated NNW-SSE, ~24"x18", required averted. Forms a pair with brighter NGC 641 4.3' NW. A mag 10 star lies 6.8' NW.

Notes by Steve Gottlieb