Heinrich d'Arrest discovered NGC 3720, along with NGC 3719, on 15 Mar 1866 and noted a faint double nebula, with a difference in RA of 9 sec and 1' in declination. His position is accurate.

400/500mm - 17.5" (5/10/86): moderately bright, fairly small, round, sharp concentration. Appears smaller but slightly brighter than NGC 3719 2.2' WNW.

Notes by Steve Gottlieb