William Herschel discovered NGC 3911 = H III-341 = h991 on 10 Apr 1785 (sweep 394) and recorded "vF, vS, but little exceeding the stellar. 240 showed it very plainly." His position is 3' southwest of UGC 6803, within his typical margin of error.

But when John Herschel reobserved this field, he assumed UGC 6803 was new and took UGC 6795, a fainter galaxy 10' west, as his father's III-341. Furthermore, he only measured the declination and failed to measure the RA for either object (as they were past the meridian), but adopted his father's RA for UGC 6795 (assuming it was H. III-341). This confusion resulted in the CGCG and other modern catalogues reversing the identifications of NGC 3911 and NGC 3920.

The identifications given by Malcolm Thomson and Harold Corwin place the NGC labels on the historically correct galaxies, but this leaves the numbering out of order in RA NGC 3920 precedes NGC 3911). Instead, Courtney Seligman favors the NGC numbers in RA order with NGC 3911 on the western galaxy and NGC 3920 on the eastern. He also assigns "H. III-314" on NGC 3920, the brighter galaxy. This is consistent with modern catalogues.

400/500mm - 17.5" (4/15/93): fairly faint, fairly small, elongated 4:3 NW-SE, brighter core, faint stellar nucleus. NGC 3920 lies 10' W. The identifications of NGC 3911 and NGC 3920 are reversed in all modern catalogues.

Notes by Steve Gottlieb