The Hercules Cluster, Abell 2151, is a rather unusual galaxy cluster a bit under a half billion light-years distant. It is unusual for its high content of spiral galaxies. Most clusters are mostly elliptical or S0 class galaxies due to most being the result of many galaxy mergers over billions of years. Somehow this cluster has avoided this though even a quick examination of my image shows many spirals in the act of merging or at least colliding. In fact, four of them made Arp's Atlas of Peculiar Galaxies, Arps 71, 122, 172 and 272. of the four only Arp 172 doesn't involve spiral galaxies. Many other galaxy interactions are also seen in my image. I prepared an annotated image but it is so cluttered with labels maybe I shouldn't have labeled as many as I did.

This is one of earliest images and suffers from my inexperience. The data was taken back in 2007. Though reprocessed 9 years later from scratch my calibration frames were crude so loses a lot. I keep saying I'm going to retake it but it never happens. Mostly because seeing is poor when it's best positioned and when seeing is good there are so many things still on my to-do list that have never been taken that it hasn't yet happened.

14" LX 200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME