Albert Marth discovered NGC 138 = m 9 (along with NGC 139 and NGC 141) on 29 Aug 1864 with Lassell's 48" on Malta and recorded "F, eS, sbM." Marth's position is accurate.

400/500mm - 17.5" (10/8/88): fairly faint, small, oval N-S, small bright core, stellar nucleus. A mag 11 star is 1' N. Brightest in a trio with NGC 141 5' ENE and NGC 139 5' SSE.

Notes by Steve Gottlieb