William Herschel discovered NGC 4105 = H II-865 = h3378, along with NGC 4106, on 7 Mar 1791 (sweep 998) and logged "Two, within a minute of two of each other. Both F, S, R, bM. Nearly in the same parallel." John Herschel made two observations, recording on 10 May 1834 (sweep 452), "The first of a double nebula (pos 111.2° by means of 2 measures), B; R; pL; psbM; r; 25"."

200/250mm - 8" (5/21/82): elongated glow resolves into NGC 4105 and NGC 4106 just following. NGC 4105 is slightly brighter and larger but appears faint, small and round.

400/500mm - 18" (5/28/06): western member of a close, moderately bright pair with NGC 4106, just 1.1' between centers. Appears round, ~45" diameter, sharply concentrated with a bright, prominent core. The halo is fairly faint and increases in size with averted vision to ~1' diameter. This galaxy is slightly larger and the brighter of the duo. Nearby galaxies include IC 2996 lies 17' SW, IC 3005 17' SE and IC 3010 38' SE.

Notes by Steve Gottlieb