James Dunlop discovered NGC 2004 = D 215 on 24 Sep 1826 and described "a round well-defined nebula, about 20" diameter, bright at the centre." Dunlop reported 3 observations and his position is 5.5' WSW of center (relatively accurate for him).

John Herschel observed this bright cluster (h2893) on 6 sweeps: on 2 Nov 1834 he recorded "B; pretty rich; compressed cluster of stars 12m." Next he recorded "globular, B; irreg; R; 2'. The stars are easily distinguishable." On a third sweep he wrote "globular, B; S; R; comp M to a blaze of stars. Many stragglers." His position is accurate.

600/800mm - 30" (11/5/10 - Coonabarabran, 264x): bright, superb cluster, ~3' diameter. Contains a small, brilliant core and a highly resolved halo that is packed with 50 stars. The surrounding field is quite rich in both faint and brighter mag 11-12 stars. The NGC 1955/1968/1974 complex lies ~20' SW and the NGC 2014/2020 complex lies 27' SSE.

Notes by Steve Gottlieb