R.J. Mitchell discovered NGC 7398, along with NGC 7397 and 7401, while observing NGC 7396 at Birr Castle on 2 Oct 1856. A sketch was made on 23 Oct 1857 and NGC 7398 was labeled "B". On 22 Oct 1876, Dreyer measured micrometric offsets to NGC 7398 from a mag 12 star 3.8' northeast of NGC 7396.

400/500mm - 17.5" (8/21/87): fairly faint, small, small bright core.

17.5" (7/22/87): fairly faint, very small, slightly elongated, stellar nucleus. Located 4.2' N of NGC 7397 and 9.3' NE of NGC 7396 in a group.

Notes by Steve Gottlieb