William Herschel discovered NGC 4138 = H I-196 on 14 Jan 1788 (sweep 798) and recorded "cB, cL, vgbM, iF."

300/350mm - 13.1" (4/12/86): moderately bright, moderately large, elongated NW-SE, rises quickly to a small bright core, possible stellar nucleus. A mag 11 star is 2.0' NNW of center. Member of the NGC 4111 Group = LGG 269.

Notes by Steve Gottlieb