Edward Pickering discovered NGC 6620 = HN 43 on 3 Sep 1880 using a direct-vision spectroscope on the 15-inch refractor at Harvard College Observatory. Pickering noted in The Observatory (1881) this is "the smallest planetary nebula known and could not be distinguished from a 13th magnitude star in an ordinary telescope." His position is exactly 1 minute of time too far west.

Based on Crossley photographs at Lick, Curtis (1918) reported "round; about 5" in diameter; just distinguishable from a star. No structural details can be made out, although faint ansae are suspected in p.a. 70-250°..."

300/350mm - 13.1" (7/12/86): stellar planetary at 79x located 2.1' NW a mag 10.5 star. Verified with OIII blinking. At 214x and UHC filter appears moderately bright and a very small disc about 4" diameter is visible. A mag 13 star lies 0.9' E.

Notes by Steve Gottlieb