NGC7635, the Bubble Nebula.
This strange object is the result of stellar winds produced by the star visible on the lower left, causing a shock wave on the clouds nearby. The propagation is not symmetric due to the differing density of those clouds.
This picture took nearly 14 hours of 300-second H-Alpha exposures, combined with one hour of each Red, Green, Blue and Light-Pollution filtered exposures. The length of the narrowband exposures is generally problematic with my mount as guiding deviations would often cancel capture, but the location of this particular object in the sky made that impact minimal. After those sessions, I started getting haze on the guiding sensor itself from lack of proper heating, causing even more disturbance to guiding. This made me close the project.
The LRGB integrated frames were first assembled and background-corrected, stretched and had stars removed. The Ha integrated frame was then denoised, stretched, had stars removed and was enhanced with masked curve transformation and HDR multiscale processing. The stars extracted from the photometrically corrected LRGB frame and saturated to emphasise their color. In order to avoid a tint to appear when adding the stars back on the final red-tinted frame and keep their photometry correct, their blue component was saturated slightly more and their magenta component corrected.
I thank user vnc1218 on CloudyNights for his very detailed processing of the Cygnus area, which inspired me on this activity.
All exposures taken with KStars/Ekos (v3.5.0 pre-release) and INDI, using the excellent Atik Horizon 2, Skywatcher HEQ5-PRO, Orion ED80T, with Atik 314E and Orion 50mm GuiderScope for guiding. Processed with PixInsight 1.8.8 and RawTherapee 5.8.