M 81

I gathered more material for M81. Unfortunately, by December, snow had fallen, and a children's playground with several bright LED lights was built in an area near me, which significantly worsened the light pollution situation. The sky background in the December lights is over twice as bright as in October, and the four-hour stack looks worse than the old two-hour stack. It seems that for broadband imaging, I'll have to go somewhere else or buy a good light pollution filter. But a narrowband hydrogen filter is already on the way, so I'll probably switch to emission nebulae for now.

I seem to have sorted out the guiding issues. Apparently, the screws securing the finder's shoe had loosened, causing significant but stiff guiding backlash that I didn't notice because I tried not to jiggle the guide unnecessarily, and it wasn't apparent with light touches. After tightening the screws, guiding improved immediately, becoming much better, roughly as it was in summer and autumn. Total RMS occasionally dropped briefly to as low as 0.5", and overall, it stayed around 0.8-1.2" throughout the night, with rare spikes of 2-3". As a result, almost all captured frames, including color ones, made it into the final luminance stack.

I tried stacking in Astro Pixel Processor for the first time. I really liked it—quite intuitive, and the results were immediately better than struggling with DSS and GIMP, especially in terms of color, though still far from perfect.

For stacking, I used Drizzle 1.5x (just out of curiosity), and the result was scaled down by half (so 3/4 of the original size).