NGC 4631's slightly distorted wedge shape gives it the appearance of a herring or a whale, hence its nickname.  Because this nearby galaxy is seen edge-on from Earth, professional astronomers observe this galaxy to better understand the gas and stars located outside the plane of the galaxy.  NGC 4631 contains a central starburst, which is a region of intense star formation. The strong star formation is evident in the emission from ionized hydrogen and interstellar dust heated by the stars formed in the starburst.  The most massive stars that form in star formation regions only burn hydrogen gas through fusion for a short period of time, after which they explode as supernovae. So many supernovae have exploded in the center of NGC 4631 that they are blowing gas out of the plane of the galaxy. *Wikipedia

Just revising an old friend almost two years after my first attempt at imaging it, now with more knowledge and discipline.  I also didn't want to miss the opportunity to also capture the Hockey Stick as they all are though to be interacting and are often seen together.  The focal length combined with my chip size made it a really tight fit but I found a framing angle that worked.  This doesn't happen often but this night I was blessed with clear weather all night, good guiding, and everything worked.  It was a really rewarding and relaxing experience.  I only ended up discarding two subs out of the whole night.  The image was processed in PixInsight and Photoshop as outlined below.

Stacked and calibrated with darks, flats, and dark flats using with PixInsight's WBP script.

PixInsight workflow:
Cropped 2% around the edges to remove stacking/dither artifacts
Automatic Background Extraction on all channels
Stretched RGB channels with EZ Soft Stretch Script
     Combined RGB with LRGB Combination process
     BackgroundNeutralization
     ColorCalibration
     Extracted L from RGB image
     Reapplied L to RGB image with 0.300 Saturation X 2 times for color
Applied BlurXTermanator to LUM
     Stretched with EZ Soft Stretch Script
     Automatic Background Extraction
     Touchup Histogram Transformation and Curves Transformation adjustments
     MultiscaleMedianTransform
     NoiseXTerminator
     Applied L to RGB image with Chrominance Noise Reduction

Photoshop workflow:
Camera Raw Filter
     Color Mixer: Hue and Saturation adjustments
Final Histogram adjustments