Arp 320 (Hickson 57) is part of Arp’s ‘Galaxy groups’ class and consists of all of the ones at the center of this image. Starting at the top, the galaxies are NGC 3748, 3745, 3746, 3750, 3753, 3754 and PGC 36010 below NGC 3748. NGC 3751, located below these galaxies, is part of Hickson 57 but not in Arp 320. These galaxies are located approximately 400 million light-years away in Leo.
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
360 minutes total exposure – 6 hours
Imaged April 5th and 6th, 2019 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/32681747917/sizes/l