Processed the narrowband and RGB separately in PixInsight and then combined them. 5 hours integration time, mainly 5-minute exposures.

I've been photographing M51: the Whirlpool Galaxy locked in a gravitational battle with the glowing dwarf galaxy NGC5195 for years now. This is the first time I feel the result successfully captures the detail and beauty of this grand-design spiral galaxy. I combined narrowband to grab the Hydrogen details with RGB to produce the result. The palette is entirely natural (in other words, I'm using the colors captured by the one-shot color camera, not anything "mapped" using a formula like the Hubble Palette) just stretched for contrast. The total exposure time was around 5 hours.