M90 (NGC 4569, Arp 76, UGC 7786 and others) is an intermediate spiral galaxy located approximately 60 million light-years away in Virgo. Arp classifies this one as spiral galaxies with small, high surface brightness companions on arms. I believe he was referencing IC 3583, the irregular-looking galaxy above M90 although the latest distance measurements put it at approximately 28 million light-years away.
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 10x300s – 50 minutes each – binned 2x2
390 minutes total exposure – 6 hours 30 minutes
Imaged over four nights in June, 2016 and January, 2017 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/35689169871/sizes/l