Full high quality processing of this dataset on Astrobin, here and here.
The Whirlpool Galaxy, (aka M51a or NGC 5194), is an interacting spiral galaxy with an active galactic nucleus. Its companion is M51b or NGC 5195. They lie Canes Venatici, at a distance is 31 million light-years from Earth.
The data has RGB and Ha. Above is a stack + histogram on the RGB only, showing the potential of the dataset to reveal the faint nebulosity around the galaxy, once fully processed. Although no star is saturated, those 5mn exposure are sure getting close to the danger zone.
I also added a starfield mosaic (2×1) with 1mn frames, so one can change composition freely and get tighter starts than on the 5mn frame.