The M81/M82 group was the target of part three of my March madness astrophotography. March was the clearest month I have had since I started doing this and I managed more total integration time than I usually get in a whole season. Galaxy season is difficult for me with a little refractor setup (382mm focal length and 2.0 "/px), but I've been having a lot of fun this spring exploring what I can do with even this little setup. This is a very big improvement over my previous attempt, which admittedly wasn't something I spent too much time on. M81/82 is in an ideal sky location for me, so it was time to give it a real try with all my clear nights in March.

For me, the biggest effect of the long integration times that I see is that it gives more flexibility in stretching the image background. My main processing goal continues to be to force myself to leave a little noise in the background and let it be a little more natural-looking rather than over-darkening it. With short integration times (particularly galaxy targets), my background tends to be so noisy that is tough to do, but, at 18 hours, I find I can stretch this image a lot of different ways and it is a lot more flexible while still looking nice. For whatever reason, I liked the stretch that APP does by default better than what I was getting from PI even with some trial-and-error with STF, so I ended up doing a little background smoothing in PI, then moving back to APP for stretching.

I spent a session using the L-Extreme filter to try to accentuate the hydrogen forming regions in M81 and it also really made the hydrogen jet in M82 pop out a lot more clearly. I am actually uploading the raw L-Extreme session stack as a revision just because it is a fascinating image on its own - I have done absolutely nothing to that one except integrate it, do a background light pollution gradient removal, and used the default APP stretch. So that's basically what I get from a narrowband image session.

With all the suburban light pollution, I just don't get the deep blue coloring in the spirals that people in dark sky sites seem to get (more like shades of gray here), but I like that I got some good definition in the two main galaxies. Some of the dust lanes in M81 are evident, and the hydrogen jet in M82 of course. I was really excited to see that I managed to preserve the irregular dwarf satellite (called PGC28757 or Holmberg IX) that orbits M81. I could see it in post-processing and tried hard not to wipe it out in background smoothing. I then realized that there are a whole lot of other tiny galaxies visible in the image (some only a few pixels), so I am also uploading an annotated version to help see some of them. Really cool!

April is usually a rainy month here in the northeast US, so I do not expect a whole lot of outdoor time this month. May is usually nice, so hopefully next month will be a good start to the summer imaging season. Meanwhile, I have one more galaxy image to process from March (Leo triplet), and I'm happy I managed to get a lot of interesting images from my little setup this spring.