English: The Pacman Nebula (IC11/NGC281/Sh2-184) is a bright emission nebula part of Cassiopeia about 9200 light years from us. The nebula derives its name from the video game and in this case, the nebulosity is spans a diametre of 92 light years (so perhaps bigger than its name suggests but very small in the context of the rest of the universe). It contains several dark nebulae within it known as Bok globules, a multiple star in the middle (B 1 or beta 1, which is a quintuple system), as well as the open cluster IC1590.

This, like the Wizard Nebula, a popular target for narrowband astrophotographers. The only difference between this image and the last one I did of the Wizard using this almost exact setup (FC100DF at f/7.4) is a Starlight Instruments microfoccuser (MPA-TAK2.5) I installed which let me fine tune the focus which wasn't possible with the factory origin Tak. I had been using the coarse focus which was tolerable at f/4.9 but at its native focal length you can see the difference in the detail and the lack of fuzziness (I'm quite positive my seeing was about the same; average). The double star in the middle of the nebula, and part of the quintuple system, is partly resolvable as two half-spheres.

I finally had some success applying a starless technique in PixInsight and I've included versions of the nebula (https://www.astrobin.com/h9xku6) without stars (C) and also an image processed without stars and then the stars added back (B). An additional colour choice is (D) since I find the SCNR palette to be repetitive at times, and as always the Ha only image is (E):

Both the main image (A) and the reconstituted starless image (B) look pretty good, with subtle differences that I think will come down to preference. There's some colour noise I was able to tame with TGVDenoise but I've yet to figure out how to sharpen details while avoiding noise entirely (deconvolution is the next thing I need to learn). Until then, the minimally processed Ha image is where you can see the minute details the most