by Rod Pommier
Telescope/Mount: Celestron Compustar C14 with 0.75x focal reducer (f/8.3). Camera: SBIG STL11000M with Baader Planetarium L,R,G,B filters.
Location: Pommier Observatory, Portland, OR, USA. Dates: 2012-05-09 through 2012-05-14. Exposures: L:R:G:B=275:80:75:75=8hrs:25min total exposure.
M101 imaged in May of 2012 shows that the supernova PTF11kly is still glowing. The supernova can be seen along the 5 o'clock radial from the core, about 2/3 the distance from the core to galaxy's edge, It appears distinctly blue in color. The supernova was a Type Ia discovered on 2011-08-24 by the Palomar Transient Factory. It peaked at magnitude 9.9 in mid September, 2011. Imaging it last summer and fall was not possible because my view of it from my observatory dome was blocked. Reports indicated it dropped to magnitude 3 by November. However, I was delighted to see it still glowing when the Oregon weather cleared in May with the galaxy high in the sky.
M101 is a class Sc spiral, with a small nuclear bulge and is considered a superb example of a "grand design" spiral well developed arms with highly branched dust lanes. The nucleus is decidedly off center and spiral arms with clouds of hot blue supergiant stars can be seen to be flung well away from the galaxy's main disk. Other blue star clouds with HII regions populate the main spiral arms. The shape of the spiral arms and burst of star cloud formation is thought to be due to tidal interaction between M101 and one or more of its 5 known companion galaxies. Many of the star clouds have their own NGC designations. M101 has a diameter of 170,000 light-years and is 21 million light years away.