Whirlpool Galaxy (Messier 51)
This galaxy is currently merging with a second, smaller, galaxy known as NGC 5195 or Messier 51b.
I took this image using my Canon EOS 400D using a 70-210mm f/4-5.6 lens. This image was taken at 200mm (320mm if you include crop factor of sensor) at f/5.6
Each sub frame was a 1" exposure.
Total exposure time was 2hrs 3mins (123 frames)