William Herschel discovered NGC 5987 = H II-765 on 25 May 1788 (sweep 843) and recorded "pF, vS." Heinrich d'Arrest measured an accurate position as well as the mag 10 star that precedes by 7 sec of time and just under 1' north. The UGC PA = 165° is incorrect and the error is repeated in the RC3 and Deep Sky Field Guide.

400/500mm - 17.5" (6/14/96): fairly bright, moderately large, very elongated 4:1 SW-NE, 2.0'x0.5'. Prominent, high surface brightness core with much fainter extensions. A mag 10.5 star is 1.3' NW of center. Located 11' NE of mag 6.5 HD 140117.

600/800mm - 24" (6/21/17): at 375x; bright, fairly large, very elongated 4:1 WSW-ENE. Very strong concentration with a very bright core and occasionally stellar nucleus. The halo is much more evident on the northern side of the core, creating an asymmetric appearance. It was quickly apparent there was a sharp light cutoff (dust lane) just south of the core, roughly paralleling the major axis. A low surface brightness portion of the galaxy on the south side of the lane was mostly seen on the southwest end of the galaxy. A 10th mag star is 1.4' NW of center.

Notes by Steve Gottlieb