The Bubble nebula (NGC 7635) and the Lobster Claw nebula, is based on a nights worth of data taken at the end of Sept 2022 and the evening of 24th Oct 2022. The 24th Oct had no moon.
We are looking at an area between Cassiopeia and Cepheus (the white rectangle). This is a rich area of nebulosity and in the Northern hemisphere at the end of October this is high overhead, an ideal area to image.
As can be seen below there is a lot going on this this field of view. NGC7635 the Bubble Nebula, the "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star. It is 7-10,000 light years away.
M52 an Open Cluster around 152 million years old, 4600 Light Years away. The "bubble" is created by the stellar wind from a massive hot, 8.7 magnitude young central star, SAO 20575 and is within the constellation Cassiopeia.
NGC 7538 is 9,100 light years away, emission and reflection nebula which is home to the biggest yet discovered protostar (young star) which is about 300 times the size of our whole Solar System.
NGC 7510 another Open Cluster of stars 11,400 light years away around 10 million years old.
Capture
2022-08-27
Exposure at ISO800, 240s using the Optolong L-Enhance Filter
Lights - 77
Darks - 12
Flats - 11
2022-10-24
Exposure at ISO800, 240s using the Optolong L-Enhance Filter
Lights - 154
Darks - 12
Flats - 30
Biases with 80 images taken at 1/4000th second for ISO800, replacing the previous master which was 6 months old
Pre-Processing
After registration of all sessions data total of 231 * 4m = 15h24m.
Removed:-
f = 3.3
r=0.8
w=5
147 images remaining, high cloud and a period 2 hours of thicker cloud meant that my normal parameters of rejection had significant impact on the number of images left. I was tempted to raise one of these parameters (especially the weighted FWHM, moving from 5 to 6 would bring many more minutes of integration time), I decided to stick to quality of image rather than quantity.
Stacked 147 * 4m -Total Integration Time = 9h48m
Post Processing
Siril
Crop - fairly minor to remove one corner of elongated stars and snip off the stacking artefacts
Background Gradient
Colour Calibration Photometry
Deconvolution, Kernal size of 0.7
Asinh Stretch - 3 iterations with stretches of (30,30,7)
Histogram Stretch
Green Noise Removal
Starless and Stars created using Siril Pixel Maths and Starnet++.
Once we have a TIFF (16 bit version) of Starless move into PS.
Photoshop Processing
Levels
Curves
Raw - Highlights and Contrast
Raw - Texture
Raw - Clarity
Raw - Colour Contrast
Raw - Noise Reduction
Raw - Saturation and Vibrancy and Shadow
Create FIT version of TIFF file output from PS using Siril
Once back from PS then Pixel Math Add the Stars back into the FIT version of the Photoshop processed TIFF file using the formulae (starless+(0.8*stars)).
Created JPG version.
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