Wilhelm Tempel discovered IC 4173 = Big. 315 = NGC 4933sw around 1882 with the 11-inch "Amici I" refractor near Florence, Italy. In his fifth discovery list, he described in the narrative portion, "In case of nebula NGC 4933 I made the remark years ago: certainly double, has a bright stellar nebula south preceding, 13m in the middle; the north following is large; Distance from each other a little over 1 '. A later remark is: fine elongated nebula with two knots, the brighter one north; on the southern tip of a faint stellar nebula"

Bigourdan independently resolved the two components (Big. 315 and 316) on 16 Apr 1895 while searching for NGC 4933, but he assumed these were new objects. Bigourdan is credited with the discovery in the IC. See NGC 4933 for this story. Gerard de Vaucouleurs assigned the letter suffixes NGC 4933A (for the southwest galaxy) and NGC 4933B in the 1964 "Reference Catalogue of Bright Galaxies".

400/500mm - 17.5" (5/17/90): very faint, extremely small, round. This is the fainter southwestern component of a double system with NGC 4933B in a common halo.

900/1200mm - 48" (4/21/17): IC 4173 = NGC 4933A is the southwest component of an interacting system. At 488x it appeared bright, fairly small, round, 15" diameter. Strongly concentrated with a very small bright nucleus and thin halo. A tidal tail extension (either from NGC 4933A or 4933B) juts out towards the southwest ~20". On the east side the halo merges with NGC 4933B [centers separated by 45" SW-NE].

Notes by Steve Gottlieb