The Cave Nebula is a dark cloud of gases and dusts within a group of emission and reflection nebulosity. The glowing rim that gives shape to the cave is illuminated by ionized gases by young stars. The nebula is around 2400 light-years away in the region of Cepheus. The image is the result of a total of 14 hours integration across multiple nights:- Ha: 5-6-7th November 2021
- O3: 28-29th October 2021
- S2: 28-29th October 2021, 2nd,3rd, 6-7th November 2021
The image is fully processed in Pixinsight
PreparationAll started calibrating each light with dark (from my library) and with flats (taken each nights - flat & dark flats) with
ImageCalibrationA quick
CosmeticCorrection and the
SubframeSelector to weight all the lights.
I took the frame with lowest FWHM as referebce to align all the channels with
StarAlignment and stack them with
Image IntegrationLinear Phase per channelAn initial round of
MureDenoise to start leads to some nice 'free' noise reduction
I extracted the background with
AutomaticBackgroundExtractor, because honestly I don't feel confident to use DynamicBackgroundExtractor when there is nebulosity everywhere
I use
LinearFit to balance the colors
Linear Phase channel combinedI use
PixelMath to obtain the HOO or the SHO versions
It's necessary to start preparing some mask: the star mask using the
Starnet process is a good place to start. After that a simple luminance extraction will give a B&W mask
I create some mask and apply some soft round of
MultiscaleLinearTransform for denoising, especially the background
I love the
PSF Image creator script by Hartmut V. Bornemann to obtain the PSF image for Deconvolution
I use one round of soft
Deconvolution, selecting the starnet starmask for deringing
Nonlinear phaseAt this point I linearize the image and work on the
CurveTransformations with some
ColorMask to obtain the colours I like the most. I try to do small modification each time
I use
Convolution and then
LRGBCombination to reduce chrominance noise
I crop the files to the format I like
I am no expert, but I like to experiment different processes based on what I find online from other Astrophotographers like me.
You can see the editing process (and the trial and error of course) of how I reached the final HOO version on the recording of my live streaming on
Youtube .
I usually stream also on
Twitch .
I hope you like it
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