Édouard Stephan discovered NGC 5421 = St XI-22 on 9 Jun 1880. He noted two very faint stars were involved - one of these is mostly likely the southern component of this interacting pair.

400/500mm - 17.5" (7/16/01): fairly faint, fairly small, irregular shape, ~1' diameter. Very unusual appearance like a faint, partially resolved cluster as a couple of faint "stars" are involved. The star is just off the southwest side and a fainter mag 15 star is attached at the southeast end. At moments, a stellar nucleus further confuses the observation. The "star" at the southeast end is VV 120c = PGC 49949, a compact interacting companion.

600/800mm - 24" (7/6/13): this mag 17.1V companion to the NGC 5421 = Arp 111 (double system) was intermittently glimpsed but confirmed at 322x! Situated just 50" S of the center of NGC 5451.

24" (7/6/13): at 282x, this interacting pair (Arp 111) appeared moderately bright, fairly small, elongated 3:2 NNW-SSE but irregular. Contains a very small, bright nucleus. A non-stellar knot companion (VV 120c) appearing like a second bright "nucleus" was visible at the southeast end of the halo. At 322x, VV 120c was easily resolved and appeared faint to fairly faint, very small, round, 10" diameter. A mag 15 star is just off the southwest side. MCG +06-31-046 at mag 17.1V, is just 1' S of the pair and was glimpsed several times for brief moments and confirmed at 322x.

900/1200mm - 48" (5/3/19): this striking interacting pair (Arp 111) consists of a tidally disrupted spiral on the north side and a compact elliptical or lenticular on the south side, separated by 20" between centers. At 613x, the central core region or bar of the spiral appeared bright, fairly small, elongated ~2:1 N-S, ~0.3'x0.15', with a very bright nucleus. A faint spiral arm was easily seen attached at the north end and extending directly west, making an angle of perhaps 110° with the central region. This arm spread out a bit as it faded at its west tip. The southern spiral arm, which extends east, was seen as a dim glow but lacked a distinct edge and merged into the low surface brightness halo on the east side. The southern component (VV 120c) appeared fairly bright, fairly small, round, 0.3' diameter, small bright nucleus.

MCG +06-31-046, a third component of this system, is situated 1' S and appeared faint, fairly small, slightly elongated SW-NE, 20"x15", low even surface brightness. A mag 15 star is 0.5' NNW.

Notes by Steve Gottlieb