The Bubble Nebula (NGC 7635) is about 7000 light years from us and 7 light-years across.  The massive O star responsible is at the lower right side of the Bubble, well off center. The stellar wind from this 45 solar mass star is crashing into the cold dust at 4 million miles per hour, forming the bubble. That gas is denser on one side, hence the asymmetry of the bubble. The Bubble illumination is dominated by OIII, while the cooler and denser pillars of gas and dust, which are much like the Eagle Nebula's "Pillars of Creation, glow due to Halpha and NII (both of which should be picked up by the Ha filter used to collect this raw data). I love the color contrasts and the violent turbulence produced as this bright O star ages, as it is licked by the flames around it. The star will be short lived on stellar terms, it is only 4 million years old, and will likely supernova in 10 million to 20 million years. This will destroy the current Bubble, but of course add a new light show that will surely be spectacular.

Data from the Royal Astronomical Society of Canada Robotic Telescope
Location               Sierra Remote Observatories, Auberry, California, 2021 Sep-Nov
Telescope           RCOS 16" f/8.9 (3550mm focal length)
CCD Camera       SBIG STX16803 16MP (4096 x 4096)
Mount  Paramount ME
Filters    SBIG RGB, Ha (7nm), OIII (8.5nm), SII (8nm)
Narrowband: 25.5 hours, RGB: 45 minutes
Narrowband (Ha, SII, OIII): 17 each at 1,800 s, 1x1, Flats = 10
RGB: 5 each at 180 s, 1x1, 5 flats
Bias=16, Darks=16

I used DeepSkyStacker to calibrate, register and stack the Level 3 data, then Startools for the bulk of my image processing. For the composted image I chose SHO using a Hubble Space Telescope palette, with a Lum channel of Ha+SHO color channels. I wanted to bring out the bright blue of the Bubble Nebula contrasting with the red/gold of the clouds: to do so ultimately for the SHO I mixed the color channels (60SII+40Ha, 30SII+30Ha+40OIII, OIII). Then I did a digital development stretch, local contrast, multi-scale sharpening, color balance, a gamma multiply composting, followed by multi-scale noise reduction. A separate RGB stars image was also developed, using Ha as the luminance, but emphasizing the stars over the nebulosity. I used Photoshop for the final composition: I removed stars from the SHO image using the StarXterminator Plugin, and did my final color balance. I then used a manual multi-scale unsharp mask (following the APF-R protocol) to bring out detail, and noise reduction using the Topaz Denoise AI Plugin low light module. Finally I added an RBG star screen layer.