William Herschel discovered NGC 5910 = H II-400 on 13 Apr 1785 (sweep 399) and noted "F, pL, easily resolvable." On 28 Apr 1788 (sweep 835) he logged "eF, vS, may be a few stars." He position is pretty accurate, though. Neither JH nor d'Arrest made an observation of this galaxy (brightest in HCG 74).

400/500mm - 17.5" (7/8/94): brightest member of HCG 74. Fairly faint, small, round, 30" diameter, weak concentration. The observation is confused by a companion (HCG 74B) that is attached at the SSW end, just 20" between centers. HCG 74B popped into view with averted vision and looked like a knot at the edge. A faint mag 14/14 double star close west is collinear and a mag 13 star is 3' WSW. UGC 9813 lies 8.0' SW.

600/800mm - 24" (7/18/17): NGC 5910 is a triple system consisting of HCG 74A (middle), 74B (south) and 74C (northeast). The main galaxy appeared fairly faint, fairly small, round, 20" diameter, slightly brighter nucleus. HCG 74B, just 20" SE at the edge of the halo, appeared faint (visible continuously), very small, round, 10"-12" diameter. HCG 74C, only 18" separation at the NE edge of the halo, appeared very faint, extremely small, round, 6" diameter. The combined glow of the three galaxies spanned ~50" SSW-NNE. HCG 75D is 1.8' S and appeared very faint, extremely small, round, 8" diameter. A mag 14.5/14.5 double [18" separation] is 1' W.

Notes by Steve Gottlieb