William Herschel discovered NGC 2558 = H III-606 = h499 on 13 Feb 1787 (sweep 698) and recorded "vF, S." John Herschel logged it on 17 Mar 1831 (sweep 334) as "pF; R; psbM; and then a feeble atmosphere 25"."

400/500mm - 17.5" (1/1/92): faint, small, elongated 3:2 NNW-SSE, gradually brighter halo, small bright core. Member of Cancer I galaxy cluster.

Notes by Steve Gottlieb