Arp 26, more famously known as M101 made Arp's atlas under the category of spiral galaxies with one heavy arm. Located in Ursa Major its distance is rather uncertain. An average of many comes to about 20 million light-years. Arp's comment on this entry reads "Note straight arm, bright knot on east appears almost stellar." I took this image while supernova SN 2011fe was near maximum brightness. It is marked at the bottom of my image between tick marks. M101 is classified as SAB(rs)cd HII by NED, SBc by the NGC Project and SAB(rs)cd? by Seligman. While recorded in Messier's list it was actually discovered by his close friend Pierre Méchain on March 27, 1781.

I've included an image taken on August 25, 2011 shortly after the discovery of the supernova and well before it reached maximum brightness. A second taken on September 24, 2011 shows it one day after maximum brightness as it was cloudy the night of maximum brightness.

Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp26.jpeg
SEDS link: http://messier.seds.org/m/m101.html

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME both supernova images