William Herschel discovered NGC 493 = H III-594 = h105 on 20 Dec 1786 (sweep 655) and logged "vF, mE, bM, 3.5' long, 1.5' broad." John Herschel reported on 20 Dec 1827 (sweep 113), "vF; L; E pos by diag 60°±; lbM; 90" length."

400/500mm - 17.5" (11/27/92): fairly faint, fairly large, very elongated 7:2 SW-NE, 3.5'x1.0', weakly concentrated.

Notes by Steve Gottlieb