Heinrich d'Arrest discovered NGC 6566 on 27 Oct 1861 with the 11-inch refractor at Copenhagen. His single position is 1.4' too far north. He mentions a mag 16 star is near. This may be either of the stars mentioned in my observation.

400/500mm - 17.5" (7/19/90): very faint, extremely small, round. A mag 15 star is 0.6' W of center and an extremely faint mag 16 star is at the NW edge.

Notes by Steve Gottlieb