Albert Marth discovered NGC 2720 = m 137 on 10 Mar 1864 and noted "F, S, R, bM." His position matches UGC 4710. Wilhelm Tempel also measured the position in list I-23 and noted it was certainly equivalent to Marth's nebula.

400/500mm - 17.5" (3/29/89): faint, very small, slightly elongated ~NW-SE, very small bright core.

Notes by Steve Gottlieb