William Herschel discovered NGC 1138 = H III-580 = h274 on 24 Oct 1786 (sweep 620) and remarked "Suspected. resolvable, 1 or 2 stars visible in it." John Herschel gave a more complete description on 23 Dec 1831 (sweep 389), "vF; vS; R; gbM; 10"; makes isosc triangle with 2 st 15 mag".

400/500mm - 17.5" (10/24/87): fairly faint, small, round, bright core, faint stellar nucleus. Forms an equilateral triangle with a mag 13 star 0.9' S and a mag 12.5 star 0.9' SE.

Notes by Steve Gottlieb