NGC 4631, the Whale Galaxy, is the edge-on barred spiral galaxy at bottom left of the full field. It is approximately 30 million light-years from Earth in the constellation Canes Venatici. Beneath NGC 4631 is its close companion the dwarf elliptical galaxy NGC 4627, also known as the Pup. NGC 4631 has a core of older, yellow stars surrounded by young blue stars. It has a dark equatorial dust lane and many emission nebulae glowing with the magenta of ionished Hydrogen. The central region of the galaxy is a starburst region where new stars are rapidly forming.
At top right of the field is the highly distorted pair of interacting galaxies NGC 4656 and NGC 4657, also known as the Hockey Stick Galaxies.
These galaxies are all members of the NGC 4631 group.
There are some faint stellar streams associated with NGC 4631. I can make them out faintly in the data but haven't been able to produce an image that shows them well yet. Still working on it...
Acquisition credit: Scott Johnson, Augusto Hernandez, John Kasianowicz, Daniele Malleo, Jose Mtanous and Rick Stevenson
Processing credit & copyright: Rick Stevenson
Scope: Ceravolo C300 @ f/4.9 = 1470mm FL
Mount: AP1100
Camera: FLI PL16803
Focuser: Atlas
Filters: Astrodon
Guiding: Lodestar II / Tak guide scope
Image scale: 1.26 arcsec/pixel (Drizzled/downsized)
Exposures: 34x1200s R, 28x1200s G, 36x1200s B, 85x600s L, 55x1800s H (74.3 hours)
Processing: PixInsight 1.8.5
High res versions are on Astrobin. Crop in full res:
https://www.astrobin.com/full/339710/B/ Slightly downsized full field:
https://www.astrobin.com/full/339710/0/