Albert Marth discovered NGC 7731 = m 588, along with NGC 7732, on 27 Oct 1864 and noted "F, S."

400/500mm - 17.5" (11/30/91): fairly faint, small, elongated 3:2 ~SW-NE, small bright core. A mag 11 star is 1.3' E. Forms a close pair with NGC 7732 1.4' SE.

600/800mm - 24" (11/24/14): fairly faint, fairly small. Sharply concentrated with a brighter "bar" oriented SW-NE within a very faint halo increasing the size to ~30". A mag 11 star is 1.3' E and NGC 7732 is 1.5' SE.

IC 1504 lies 17' NNW and appeared fairly faint, fairly small. Sharply concentrated with a brighter "bar" oriented SW-NE in a very faint halo increasing the size to ~30". A mag 11 star is 1.3' E

900/1200mm - 48" (10/26/16): at 610x; bright, moderately large, slightly elongated E-W, 1.0'x0.8', well concentrated with a slightly elongated bright core SW-NE and a sharp, very bright stellar nucleus! Situated just 1.3' W of a distracting mag 11 star. Forms a striking pair with NGC 7732 1.5' SE.

Notes by Steve Gottlieb