With the recent supernova (SN 2023ixf) eruption in M101, the Pinwheel Galaxy, many like me have been spending quite a bit of time acquiring frames of this iconic target.  I had already acquired many hours of fresh frames prior to the SN for the express purpose of making a glamorous LRGB-Ha image, wishing to also include data from last year.  But then the SN was announced, and I was excited to discover that I had a whole night's worth of frames showing the rapid brightening of this transient event, which I recently posted here.  This was followed by even more imaging over the following week.  Here's my composite image from just last week:



Now I have collected all those M101 frames, from before, during and after the SN, to produce this deep exposure image.  This is an unusual amount of integration that goes well beyond what I normally devote to my images, and the result is, at least to me anyway, fascinating.  The detail of M101's faint nebulosity is drawn out more than I can normally achieve with more modest integration time from my suburban backyard.  I've always been fascinated by the dim, often invisible, thin arms below and faint, thick arms above as seen in this image.

M101 is a grand design face-on spiral, a huge galaxy perhaps twice the size of the Milky Way, 168 kly (51.9 kpc) across, with something like 1 trillion stars.  By my estimation, it is comparable in size to the Andromeda Galaxy.  It is about 20.9 Mly (6.4 Mpc) distant, which, although beyond the Local Group, is still considered a "close" neighbor of ours, relatively speaking.  It has a high number of H II regions, which I was able to accentuate with some H-alpha data.  I blended this in using the formulae I detailed here from an earlier, much wider field of view image posting of M101.  The galaxy is asymmetrical due to tidal forces with neighboring galaxies.  Referring to this current original, wider field image and the annotated Rev. D image, the most prominent companion in view is NGC 5477 to the left, a dwarf galaxy that orbits M101.  There are several more outside of this view, one or more of which have caused the odd shape of M101 and appearance of the top arm being partially ripped off through past interaction.

I won't go into more detail about SN 2023ixf since it has been prominently and popularly featured over the past couple of weeks.  In this image, since I combined frames from before, during the rapid brightening phase, and after, when the SN was more stable and quite bright, its image is odd-looking, and I did not do much to "fix" the fact that I was combining all these frames from different times.  When preparing the RGB image for the color channels, however, I actually erased the SN image altogether, otherwise the final image would have had a funky kaleidoscope of colors showing odd and unnatural color rings.  I was content to just let it be white and weird-looking.  The rest of the deep image is static, so the SN can be ignored if it gives offense.

Of even more interest to me in this image are the myriad of dim background galaxies that such a deep exposure can draw out.  For example, in the Final Image, Rev. E, I have cropped the full image on just M101, but even in this frame one can see many distant background galaxies.  Looking at the center left of this view, one can see what appears to be a tight group of galaxies.  As an example, there is a distant double-armed spiral in this group, with longer axis oriented vertically in the image.  I looked up its location in the Aladin Lite Viewer online and found it is 2MASS 14043987+5423161, with cited distance on the order of 330 Mpc (1.08 Bly)!  It is hurtling away from us at about 24,000 km/s with a redshift of 0.08.  By comparison, M101's redshift is about 0.0008.  I encourage the reader to zoom in on the original image at full view to peruse all those little distant galaxies.  I enjoy doing this with such images, the closest we can get to intergalactic travel, but perhaps instead taking a journey in Carl Sagan's Ship of the Imagination:



Well, I hope you enjoy my deep integration image of M101 with nebulosity and H II region detail, the myriad of distant background galaxies, and the SN combined at various stages of its existence.  I'll no doubt return to this galaxy again.  Thank you for your interest, and, as always, your comments and suggestions are greatly appreciated!