Arp 42 consists of NGC 5829 (UGC 9673, PGC 53709, VV 7 and others), the spiral and IC 4526, the companion. Arp has these in his spiral galaxies with low surface brightness companions on arms but IC 4526 appears to be much further away so the only interaction might be visual. These galaxies along with the others around them are part of Hickson Compact Group 73. All of these are located in Bootes.
Luminance – 28x600s – 280 minutes – binned 1x1
RGB – 10x300s – 50 minutes each – binned 2x2
430 minutes total exposure – 7 hours 10 minutes
Imaged over four nights in May, 2017 and January and March, 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/26122058337/sizes/l