William Herschel discovered NGC 7231 = H II-606 = h2153 on 24 Oct 1786 (sweep 620) and recorded "F, S, easily resolvable or rather a patch." His position is nearly 5' too far northwest. A second observation was made on 19 Oct 1788 (sweep 868), though he just noted "eF, r[esolvable]." JH made the single observation "a most eF nebulous appearance, which is probably a few minute stars. No other near." His position is accurate to within 1'.

400/500mm - 17.5" (8/8/91): faint, fairly small, elongated 3:2 E-W, unconcentrated glow. Two mag 14 stars are off the south edge. Located 15' SW of mag 5.5 SAO 51783 just off the edge of the field. This object appears as an unresolved patch in a rich Milky Way field (ZOA galaxy) as it is located just 9° from the galactic equator.

Notes by Steve Gottlieb