William Herschel discovered NGC 3605 = H III-27 = h844, along with NGC 3607 and 3608, on 14 Mar 1784 (sweep 170). He recorded "Three nebula of different sizes; all brightest in the middle & R. The largest is that in the middle NGC 3607] & is of a considerable size; that on the north [NGC 3608] is a good deal smaller. The most south of them [NGC 3605] is much smaller than either of them, so that at first I did not immediately perceive it."

300/350mm - 13.1" (2/16/85): fairly faint, small, round, small bright nucleus. In a group with brigtest member NGC 3607 3.0' NE.

600/800mm - 24" (5/27/17): fairly bright, moderately large, oval 2:1 SSW-NNE, 0.8'x0.4', sharply concentrated with a small very bright core that increases to a quasi-stellar nucleus. Close pair with brighter NGC 3607 3' NE. Member of the large group USGC U376.

Notes by Steve Gottlieb