Ralph Copeland, while an assistant at Birr Castle, discovered NGC 3748 and 3 other members of "Copeland's Septet" on 5 Apr 1874. He noted "pB; pS; R" and labeled it Delta on the constructed sketch made on 13 Apr 1876. See NGC 3753.

400/500mm - 17.5" (5/11/96): very faint, very small, round. Third of three in a tight trio within Copeland's Septet with extremely faint NGC 3745 1.1' W and NGC 3746 1.6' SW.

17.5" (3/19/88): third of 7 in Copeland's Septet. Extremely faint and small, round. This galaxy is the third in a close trio with NGC 3745 1.1' WSW and NGC 3746 1.6' SW. Located 2.9' NNW of NGC 3753.

900/1200mm - 48" (4/16/15): at 488x; moderately bright, fairly small, slightly elongated NW-SE, 0.4'x0.3', small brighter core. HCG 57H (the "8th member" of Copeland's Septet), is 0.9' SSE and appeared faint to fairly faint, very small, round, 12" diameter.

48" (2/20/12): at 488x, HCG 57H = PGC 36010 was easily seen 0.9' SSE of NGC 3748. It appeared faint, very small, round, 12" diameter.

Notes by Steve Gottlieb