William Herschel discovered NGC 3577 = H III-723 on 1 Apr 1788 (sweep 822) and noted "eF, vS. It is south preceding the foregoing nebula [NGC 3583]." His position is 4.5' north of UGC 6257, but this is the same offset as[NGC 3583, so the identification is certain.

400/500mm - 17.5" (4/6/91): very faint, small, slightly elongated WNW-ESE. A mag 11.5 star is 30" SE of the outer halo and 1.2' from center. Forms a pair with NGC 3583 5.2' NE.

Notes by Steve Gottlieb