This is the so-called Pacman Nebula in Cassiopeia. Also known as NGC 281. I collected 22 five minute subs over two nights with my 11″ SCT at f/1.9 using a dual narrowband filter. I’m trying a borrowed ASIAIR Pro device for image capture instead of my trusty laptop.
From Wikipedia:
NGC 281, IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way’s Perseus Spiral Arm. This 20×30 arcmin sized nebulosity is also associated with open cluster IC 1590, several Bok globules and the multiple star, B 1. It collectively forms Sh2-184, spanning over a larger area of 40 arcmin. A recent distance from radio parallaxes of water masers at 22 GHz made during 2014 is estimated it lies 2.82±0.20 kpc. (9200 ly.) from us. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.
