J.L.E. Dreyer discovered NGC 4011 on 24 Apr 1878 in one of the later observations of the cluster with the 72" and labeled as "Epsilon" on the published sketch (constructed from all observations). His notes read "vF, vS, *12m 2.5' np." The nebula was placed +/- 4' in approximately PA 112° from mag 8.3 HD 103913. The actual offsets to CGCG 127-121 = PGC 37674 are 5.4' in PA 117°. The mag 12 star (also shown on the sketch) is 1.4' N. This was apparently the last night that novae were discovered at Birr Castle.

600/800mm - 24" (3/22/14): very faint or faint, small, round, 15" diameter, very weak concentration. Located 3.7' SE of NGC 4005 and 5.4' NW of NGC 4015.

Notes by Steve Gottlieb