Object name: ARP023
Arp 23 is a one-armed spiral galaxy in Canes Venatici. It is also known as NGC 4618. Oddly there are two one-armed spirals in the image but only the larger made it into Arp's atlas. The smaller is NGC 4625. Redshift puts Arp 23 at 36 million light-years distant while two Tully-Fisher measurements at NED say 25 million light-years. NED classifies it as SB(rs)m HII while the NGC Project says simply SBm and Seligman agrees with NED. The galaxy was discovered by William Herschel on April 9, 1787. It made the original Herschel 400 list. My notes from April 28, 1984 with my 10" f/5 at up to 150 power on an excellent night read: "Bright with little detail seen, Didn't note the ringtail even though a great night. Other galaxies in the field may have distracted me, especially the one to the north (NGC 4625 I now know) which seemed bright enough to be plotted on the Tiron Atlas but was not."
Related Designation(s):11HUGS 301, 2MASS J12413288+4109029, 2MASX J12413284+4109027, 2MASXi J1241327+410903, AKARI J1241329+410915, ARP 023, ARP023, CGCG 1239.1+4126, CGCG 216-017, HDCE 0706 NED076, HOLM 438A, IC 3667, IRAS 12391+4125, IRAS F12391+4125, KPG 349A, KUG 1239+414, LDCE 0867 NED122, LGG 290:[G93] 010, MCG +07-26-037, NGC 4618, NSA 162248, PGC 042575, SSTSL2 J124132.88+410902.9, UGC 07853, USGC U480 NED04, UZC J124132.5+410903, VV 073, WSRT-CVn [KOV2009] 65, [M98j] 170 NED64, [TCW2007] 128,