Édouard Stephan discovered NGC 3154 = St X-24 on 12 Mar 1880 and noted "F, S, R, lbM." His position matches UGC 5507.
400/500mm - 17.5" (1/23/88): faint, very small, elongated NW-SE. A mag 14 star is 1.1' N. Located 2.2' WNW of mag 8.7 SAO 99006.
Notes by Steve Gottlieb