Édouard Stephan discovered NGC 6509 = St X-36 on 20 Jul 1879 and recorded "eF, pL, irr R, lbM." His micrometric position is accurate.

400/500mm - 17.5" (7/9/90): fairly faint, fairly small, slightly elongated 3:2 E-W, weak concentration. A mag 14.5 star is at the east edge 41" from the center. Located 7.9' S of mag 7.1 SAO 122988.

Notes by Steve Gottlieb