I last imaged NGC 4631 eight years ago. I'm not sure what was going on that night, but the image I uploaded to my Astrobin gallery was the product of only 48 minutes of integration. Needless to say, the image was not that good! So, I decided it was time to give this target and its environs something of the treatment that they deserve.
The most prominent features in this image are NGC 4631 (the Whale Galaxy) and its neighbor NGC 4656/4657 (the Hockey Stick Galaxy). Also immediately noticeable is NGC 4627, the dwarf elliptical galaxy just above the Whale. The mutual gravitational interaction of these three galaxies has significantly warped the shape of all of them.
While nowhere near as dramatic in appearance as the three standouts just mentioned, numerous small galaxies pepper this image. Some are far more distant than the three; however, some are dwarf ellipticals that belong to the group, only recently discovered since 2010. If you are interested in the identities of the small, dim galaxies in my image, I would urge you to compare my image to the deep, annotated image of this region shot by Jim Thommes, to be found here:
http://www.jthommes.com/Astro/images/NGC4631_MN152_PI1_PS1-CrpRz-annotated2.jpg. The dwarf elliptical that belong to the Whale Group have HSC designations in Jim's image.
The Whale Group lies about 30 million years light years away. The Whale and the Hockey Stick are both edge-on barred spirals. The Whale contains a central starburst region. Numerous short-lived, supergiant stars birthed in this region have gone supernova, blowing large amounts of gas out of the plane of the galaxy.
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