The Deep Sky Collective: Carl Björk, Thomas Bähnck, Sebastian Donoso, Jake Gentillon, Antoine and Dalia Grelin, Stephen Guberski, Richard Hall, Tino Heuberger, Jason Jacks, Paul Kent, Brian Meyers, William Ostling, Nicolas Puig, Tim Schaeffer, Felix Schöfbänker, Mikhail Vasilev
This extremely deep image of the Whirlpool Galaxy (M51) reveals vast amounts of cirrus-like nebulosity swirling around the galaxy — and also beyond, left over from its interaction with dwarf galaxy NGC 5195. Also note the red Hydrogen-alpha “shelf” that appears on the far right. This image is the product of a collaboration of 15 astroimagers and 255 hours of exposure, including 110 hours of Hα. More details are available here.