Pinwheel

Canon Rebel T5i (Modified), Canon 300mm f2.8IS II + 1.4x TC III, f4, 75 second exposure (Qty 62), ISO 1600, Astrotrac, Dark, Flat and Bias Frames, ImagesPlus, Photoshop, Lightroom.

Please view in shadowbox.

Total exposure time: 77 minutes, 30 seconds. 

The Pinwheel galaxy is a beautiful spiral galaxy found within Ursa Major.  It is located right next to the handle of the big dipper and an almost equilateral triangle can be drawn with The end two stars of the handle and this galaxy.

Its designation is Messier 101 (M101) and is dubbed the Pinwheel Galaxy for obvious reasons.  M101 is located about 25 million light years away and was discovered by Pierre Méchain in 1781.  How these amazing astronomers found these deep space objects with the technology available at the time is truly quite incredible!

Notice that there is some asymmetry with the spiral arms of M101.  It is believed that this is due to a near collision with another galaxy, and that this event caused density waves in the spiral arms to be amplified, compressing hydrogen gas and leading to bursts of star formation. -(Jerry Lodrigus) There are bright pink and red knots of ionized hydrogen gas within the spirals, however I was unable to capture this detail with this attempt.  I did not use my light pollution filter, and as a result the RAW files had a strong orange red hue to them.  Removing this cast, also removed the ionized hydrogen gas.  Perhaps I will combine this image with some frames using my light pollution filter to recover this detail.   

Of further interest, off to the left of the frame is a small (or very distant) spiral galaxy, and toward the lower right corner is another spiral (presumably) galaxy oriented end on to us.