Heinrich d'Arrest discovered NGC 6521, along with NGC 6512 and 6516, on 27 Oct 1861 with the 11-inch refractor at Copenhagen. His position (measured on 2 nights) is fairly accurate and he measured the bright wide pair of stars are 32.5 and 37.7 seconds following. Lewis Swift independently discovered all three of these galaxies on 28 May 1886 and recorded Sw. III-98 as "eF; 2 B st nr foll.". Swift's position is 30 seconds of RA too far west (same offset as NGC 6516).

400/500mm - 17.5" (6/11/88): fairly faint, fairly small, large brighter core. Bright wide pair O∑∑ = 7.2/7.7 at 55" is 4' E and detracts from viewing. Brightest in a group (WBL 650 = LDCE 1271) and third of three with NGC 6516 5.0' NW and NGC 6512 6.9' WNW.

Notes by Steve Gottlieb