William Herschel discovered NGC 4039 = H IV-28.2 = h1053, along with NGC 4038, on 7 Feb 1785 (sweep 368) and assigned a single H-designation (IV-28). See that number for more.

400/500mm - 17.5" (5/14/88): this is the southern member of the striking "Ring-Tail galaxy". Attached at the east side of NGC 4038 and forms a "tail" elongated NW-SE.

600/800mm - 24" (4/10/08 - Magellan Observatory, Australia): attached on the east end of NGC 4038 (see detailed notes) is a long "tail" or arm (this is the interacting companion NGC 4039) that curves around on the south side towards the southwest. Another very faint, but slightly larger 20" knot is embedded along the main portion of the tail roughly halfway. At the tip of the main tail was a relatively large, brighter knot that at times appeared double. Surrounding the SW portion of the tail is a much fainter outer halo extended SW-NE. This fainter halo extends beyond the tail for a few arc minutes and widens to a bulbous shape at the end. This was by far the most detailed view I've seen of the Ring-tail galaxy.

Notes by Steve Gottlieb