This little project started as just a test for adjusting field flatness and while I was waiting for my main target of the evening to cross the southern meridian. I like open clusters even though they aren't as exciting as the bright, shiny DSOs, but then I opened the first frame and immediately saw the planetary nebula [NGC2438] sitting within M46. I've never tried imaging a PN before because they are all so small that it didn't seem worth it with a small 80/400mm sized system. This one is a whole 40-pixels in diameter in my native system, but I got fascinated that I was able to see it so clearly in a single sixty-second frame. Two nights of short imaging runs later, this became a little project.

For NGC2438, I took all the frames and integrated just the small surrounding zone with drizzle to get more resolution for the inset. Drizzle usually doesn't work well for me since seeing is always so terrible, but it seemed sufficient for such a small region. I think it's incredibly cool that I can clearly see the red ring around the outside (I assume this must correspond to the initial hydrogen expulsion from the star) and the Oiii filling the interior being radiated by the white dwarf. A quick search on Astrobin doesn't show many images of this PN and only a very few with more resolution than I have. Michael Feigenbaum has a great image with some more resolution than I can do (https://astrob.in/fib42n/H/), but somebody with one of the big PlaneWave's needs to give this one a try!

There's also a second much smaller PN (pk231+4.1) I noticed in post-processing too - just a few brownish, red pixels at my resolution, but it's still incredible what I can see with this small system. These are objects I never would have known about if I hadn't pointed my telescope in that general direction.

Open clusters and star fields are really the toughest thing to process because there's nothing to distract from the background and the star quality. I have once again learned a whole lot about mask control in PixInsight and I am having better luck using it each time. With this camera, my setup really has become limited by the light pollution noise in the background, which I had to try my best to carefully control. My goal was to get the background smooth enough that I didn't have to over-darken it to hide the noise and also mask off the stars well enough so as not to damage them too much. It's a very narrow path here in the suburbs, but I got a result I like well enough.