Max Wolf discovered IC 3550 = W. IV-218, along with IC 3551, 3552, 3554, 3555, 3563 and 3564, on a Heidelberg plate taken 23 Mar 1903. He reported "F, S, lE 150°." I don't know where the letter designation NGC 4559C originates. It's not used in the RC1 or RC2.

900/1200mm - 48" (4/7/13): IC 3550 appeared as a faint, very small, 8" HII knot in NGC 4559. Appears to be detached from the galaxy on the southwest side, 2.1' SW of center and 0.8' WNW of a mag 15 star = IC 3554.

Notes by Steve Gottlieb