Arp 258 appears to be the various blue galaxies at the center of this image. Arp has these in his ‘Irregular clumps’ class. The largest galaxy is UGC 2140 (VV 143 and others). Other galaxies in this galactic mess include UGC 2140 A, B and C from south to north. These along with MCG+03-07-038 (PGC 10046 and others), the edge-on galaxy below Arp 258 are also designated as Hickson 18. These are located in the constellation Aries.
Luminance – 27x600s – 270 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
390 minutes total exposure – 6 hours 30 minutes
Imaged January 11th, 12th, 13th and 14th, 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/40046650271/sizes/l