Guillaume Bigourdan discovered NGC 3161 = Big 43 on 1 Feb 1886, along with NGC 3151, 3159 and 3161. His position matches CGCG 211-025 = PGC 29837.

300/350mm - 13.1" (2/25/84): extremely faint, very small, round. Located between NGC 3159 and NGC 3163.

400/500mm - 17.5" (3/23/85): this member in the NGC 3158 group is small and the faintest of three with close companions NGC 3159 1.2' W and NGC 3163 1.5' E. Even surface brightness and visible with direct vision.

Notes by Steve Gottlieb