Arp 99 (Hickson Compact Group 93) consists of NGC 7550 (UGC 12456 and others), an elliptical AGN galaxy at the center, NGC 7547 (UGC 12453 and others), the spiral to the right (west) interacting with it and NGC 7549 (UGC 12457 and others), the stretched barred spiral. NGC 7550 and 7547 appear to be approximately 225 million light-years away. NGC 7549 is closer at approximately 209 million light-years away. All of these are located in Pegasus.
Luminance – 24x600s – 240 minutes – binned 1x1
RGB – 8x300s – 40 minutes each – binned 2x2
360 minutes total exposure – 6 hours
Imaged October 26th and 29th, 2016 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/33843140752/sizes/l