ngc 7635 – bubble nebula

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I captured 15 hours of data on the bubble nebula between Sept 5-6th, 2020. the target is small in the field of view with my telescope focal length and imaging chip combination, but thought it might be interesting because of the unique structure of the nebula. The nebula is heavy in the Ha range of the spectrum, but also has a clear Oiii component to the bubble itself. the imaging session details are below:

imaging cameraZWO ASI 1600MM Pro
guide cameraZWO ASI290mm Mini
mountSkywatcher EQ6-R pro
telescopeExplore Scientific ED102 APO
exposure settingsfor all filters:
gain 139
exposure 180s
filtersOptolong 7nm Ha
Optolong 6.5nm Sii
Optolong 6.5nm Oiii
stacking100 Ha lights
105 Sii lights
100 Oiii lights

additional calibration for each channel
30 darks
30 flats
30 dark flats
imaging session details.

Here are the three channels to compare the underlying data. Each image is stacked, cropped, and has dynamic background extraction a stretch applied.

I was initially stuck with a very green image when I combined to RGB using pixel math. the normal approach of using curves or scnr to reduce the green just wasn’t working to leave much to work with. I did a bunch of trial and error with curves to arrive at the following image:

ngc 7635 bubble nebula in SHO

I also created a starless image of this one again just for comparison purposes:

ngc 7635 bubble nebula in SHO with stars removed

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