Arp 157 (NGC 520, UGC 966, VV 231 and others) is a galaxy train wreck. Arp has this one in his ‘Disturbed with interior absorption’ class. This irregular galaxy is the result of the merger of two spirals approximately 105 million light-years away in Pisces. Note the faint tidal tail going to the north towards faint UGC 957.
Luminance – 48x600s – 480 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
600 minutes total exposure – 10 hours
Imaged December 15th, 18th, 19th, 2017 and January 4th and 5th, 2018 from Dark Sky New Mexico at Rancho Hidalgo (Animas, New Mexico) with a SBIG STF-8300M on an Astro-Tech AT12RCT at f/8 2432mm.
LRGB - https://www.flickr.com/photos/dcrowson/38821789474/sizes/l
I took an extra couple nights of luminance to attempt to catch more of the tidal tail.