Albert Marth discovered NGC 7503 = m 528, along with NGC 7499 and 7503, on 2 Sep 1864 and noted "vF, S, stellar." His position is accurate.

400/500mm - 17.5" (8/1/87): faint, small, round. NGC 7503 is the third in a trio with NGC 7501 3.2' WNW and similar to NGC 7499 5.0' WNW but with a more compact core. Located in the core of the Pegasus II cluster.

Notes by Steve Gottlieb