Heinrich d'Arrest discovered NGC 4721 on 24 Apr 1865 with the 11-inch refractor at Copenhagen. His single measurement is accurate.

400/500mm - 18" (4/10/04): faint, small edge-on WNW-ESE, 0.6'x0.2', very small brighter nucleus. Forms a pair with brighter NGC 4721, 6.8' NNE. A mag 11 star lies 3.6' NNE, midway between NGC 4721 and NGC 4728.

Notes by Steve Gottlieb