William Herschel discovered NGC 6624 = H I-50 = h3742 on 24 Jun 1784 (sweep 232) and recorded "cL, R, vBM. The brightness appears to be at least 3/4 of the whole visible diameter, but I suppose if the altitude was more considerable a different proportion would be seen. The nebulosity appears to be of the milky kind, but from similar phenomena in low situations, I have no doubt that it is resolvable." JH made three observations from the Cape of Good Hope, first logging on 3 Aug 1834, "Globular Cluster; B; S; R; psmbM; diam 6 seconds in RA; barely resolved so as to be sure it consists of stars." On a later sweep, the cluster was "clearly resolved into stars 16m; a fine object."

400/500mm - 17.5" (5/10/91): bright, fairly small, round, 3' diameter. Very symmetric appearance as increases to a sharp, small bright core and brighter stellar nucleus. There was some resolution in the halo, particularly on the north edge. Approximately six mag 14-15 stars were glimpsed. A close mag 12/14 double star at 10" separation is 1.7' WSW of center. Located 45' SE of mag 2.7 Delta Sagittarii in a rich star field.

Notes by Steve Gottlieb