Arp 71 is one of four Arp atlas entries in the Hercules Galaxy Cluster (Abell 2151). Most galaxy clusters are made up of elliptical or elliptical-like galaxies. This one is made up of a lot of spiral galaxies which is very rare. Arp 71 belongs to his category for spiral galaxies with small, high surface brightness companions. It is located near the center of the cluster where elliptical galaxies are normally found. The main galaxy is NGC 6045 which NED and the NGC Project classifies as SB(s)c while Seligman adds a question mark. The companion, LEDA 84720, an S07 galaxy is obviously part of the cluster but may not be a true companion, but just a line of sight galaxy in the crowded cluster. NGC 6045 was discovered by Lewis Swift on June 27, 1886. I measure it at about 150,000 light-years, a very large spiral.

This data was taken September 13, 2007. I didn't have the tools to do it justice back then. I need to reshoot this one. It also contains Arp 122, Arp 172 and Arp 272. Details are in the annotated image. The annotated image shows details on many other galaxies in the cluster and beyond it.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp71.jpeg

14" LX200R @ f/10, L=6x10' RGB=3x10', STL-11000XM, Paramount ME