Edward Pickering discovered NGC 6537 on 15 Jul 1882 with the 15-inch refractor at the Harvard College Observatory. NGC 6565 was the 5th of 17 planetaries he found using a direct-vision spectroscope attached to the large refractor. He announced the discovery of the first dozen in Sidereal Messenger, Oct 1882 (no descriptions) and in Astronomische Nachrichten 2454, he noted it as "small and bright". His position in Sidereal Messenger was accurate.

Based on Crossley photographs, Curtis (1918) reported NGC 6537 as "a minute disk 5" in diameter, just distinguishable from a star. Round, with clear-cut edges; a slightly condensation at center is suspected, and a very faint ansa in p.a. 25". The huge hourglass-shapes structure visible in deep images that surrounds the central part was missed in the Lick photographs.

300/350mm - 13.1" (8/17/85): appears mag 12.0 or fainter with OIII filter at 79x. In the field SW of a mag 7 star forming the southern "star" of an arc of three stars.

13.1" (8/11/85): stellar at 166x, estimate mag V = 12.5. Just non-stellar at 220x and clearly nebulous at 360x, about 4" diameter. Appears fainter than computed V magnitude. Located 7' SW of mag 6.8 SAO 161056 and forms the east vertex of an obtuse triangle with two mag 12 stars 1.5' WNW and 2.4' NW.

400/500mm - 17.5" (8/17/01): picked up at 220x as a fuzzy mag 12 "star" forming the eastern vertex of an obtuse, isosceles triangle with two similar stars 1.5' W and 2.4' NW. Excellent view at 380x and 500x. Clearly nonstellar at the higher powers, ~5" diameter with a bluish color and occasionally a slightly brighter center.

600/800mm - 24" (7/11/18): at 225x; very small disc with a warm or ruddy color. Excellent view at 375x; very small, slightly elongated, ~6" diameter. The disc has a very high surface brightness and appears to be surrounded by a very faint thin shell. The PN forms an obtuse isosceles triangle with a mag 11.6 star 1.5' W and a mag 12.6 star 2.4' N.

Notes by Steve Gottlieb