Lewis Swift discovered NGC 6598 = Sw. I-88 on 6 Sep 1883 and recorded "vvF; pS; R; in vacancy; 3 st in a curve south." Swift's position is just off the south edge of UGC 11139 and the closest of the "3 st in a curve south" is 3.7' south-southeast.

400/500mm - 17.5" (6/11/88): faint, very small, round, weak concentration. A mag 15.5 star is at the east end.

Notes by Steve Gottlieb