William Herschel discovered NGC 3665 = H I-219 = h881 on 23 Mar 1789 (sweep 915) and recorded "vB, cL, vgmbM, iF." JH made two observations, first logging it (sweep 335) as "vB; R; pgmbM; 50"; r."

The RNGC has a typo in the declination, which is listed as 2 deg 54' instead of 38 deg 54'.

400/500mm - 17.5" (5/2/92): very bright, fairly large, elongated 2:1 SSW-NNE, 2.5'x1.3', increases to very bright core, stellar nucleus, fainter elongated halo. A mag 15 star is off the north edge.

Notes by Steve Gottlieb