Albert Marth discovered NGC 7558 = m 550 on 3 Nov 1864 and noted "eeF, neb * 13m." His position is accurate. This galaxy was probably first found by LdR or assistant Bindon Stoney on 2 Nov 1850 and noted again on 6 Sep 1855, though it was just mentioned as an additional nebula in the field, without any comment about the location.

400/500mm - 17.5" (9/7/96): extremely faint, very small, round, 20" diameter. Collinear with a pair of mag 14.5 stars oriented N-S that lie 2.5' S. This galaxy and HCG 93D = CGCG 454-015 = NGC 7553? (NGC identification uncertain) are the two faintest members of the HCG 93 quintet. Located 6' SE of NGC 7550 = HCG 93A.

17.5" (9/23/89): extremely faint, very small, round. An easy pair of mag 14.5 stars with separation 22" oriented N-S lies 2.5' S. Located 5.8' ESE of NGC 7550 in HCG 93 and faintest of four viewed.

600/800mm - 24" (12/28/13 and 9/27/19): faint to fairly faint, fairly small, slightly elongated ~N-S, ~20"x16". Low even surface brightness with an occasional faint stellar nucleus. The redshift of this galaxy is over ~70% greater than the other four members of HCG 93, so it is probably a background object.

24" (12/1/13): faint to fairly faint, small, round, 20" diameter, weak concentration. Nearly collinear with two mag 14.5 stars [22" separation] located ~2.8' S.

Notes by Steve Gottlieb