At William Herschel's original position and description (VIII 76) is a scattered group of stars involved with IC 5076 and mag 5.7 SAO 50246. Nebulosity IC 5076) is visible on the west side of a striking 5' group of stars centered on the bright star. Ten of the stars surrounding the mag 5.7 star form a semi-circle including a tight quadruple 2' SE. John Herschel's h2091 lies ~10' WSW and either object could be taken for NGC 6991.

William Herschel discovered NGC 6991 = H VIII-76 = h2091 on 27 Sep 1788 (sweep 866) and recorded "A st 6m not in H. A L star surrounded with many considerable stars, forming a brilliant though much sc[attered] cluster; the star 6m is not in the center but towards the following side." His offset points to mag 5.7 HD 199478 at 20 55 49.7 +47 25 04 (2000), which is the star involved with reflection nebula IC 5076. JH recorded two observations , but they refer to a separate group about 12' southwest! In sweep 210 he recorded "a star 9m; the largest of a cluster." His position on this sweep is 8 seconds of RA west of mag 8.4 SAO 50220 at 20 54 43.4 +47 16 50. In sweep 209 the diameter is given as 6'.

So, there are two candidates for NGC 6991. My notes described both candidates. Lynga and RNGC identify WH's group as NGC 6991. Also see Harold Corwin's identification notes and Brent Archinal's monograph on the nonexistent RNGC open clusters.

400/500mm - 17.5" (10/24/92): at John Herschel's position and matching his description for h2091 is a scattered group of approximately 20 stars in a 6' field which is located about 10' SW of IC 5076 and a mag 5.7 star. Three equal mag stars are collinear on the east side and a mag 8.5 star is on the SW side. There are no dense knots or a core and this collection of stars barely stands out in the field.

Notes by Steve Gottlieb