William Herschel discovered NGC 5821 = H III-811 on 24 Apr 1789 (sweep 927) and recorded "vF, S, E." His position (CH's reduction) is poor, but his offset from NGC 5820 is points to UGC 9648. Bindon Stoney independently discovered this galaxy on 6 Apr 1851 at Birr Castle and JH assigned two GC designations to both observations but Dreyer combined these in the NGC.

400/500mm - 17.5" (5/23/87): very faint, diffuse, elongated NW-SE. Two bright stars ADS 9474 = 6.8/7.4 at 40" located 6' SE interfere with viewing. Located 3.7' NE of brighter NGC 5820.

Notes by Steve Gottlieb