Such was the success of my previous post where I reprocessed the California Nebula I decided to try a reprocess my Orion Nebula data. In Jan this year I was using Deep Sky Stacker and Photoshop. Now it's Siril, Starless processing before heading into Photoshop. If you are interested here's the link to read all about my Post Processing workflow.
Probably the most famous Nebula in the Northern Hemisphere if not the whole sky. It is in the line of stars that make up Orions Sword, M42 is the Messier designation. Around 1,300 light years away it is visible with the naked eye and easily resolved with binoculars. One of the those objects that is actually so bright it poses a strange problem for astrophotographers in that the central region tends to be blown out.
It is roughly 1º across, which real terms it is about 24 light years. There is so much information on this object I will leave it to the reader to peruse the Wikipedia article!
My reprocessing...
There are actually a number of separate nebula, to the left of the Orion Nebula is the Running Man nebula (NGC 1977) in fact I chose not to put up the usual Plate Solve version as their were so many close annotations it was indecipherable! My previous processing of this data is shown below.
I would like to think that similar to the California Nebula reprocessing there is a marked improvement.
Capture
2022-01-19
Exposure at ISO800, 120s using the Optolong L-Enhance Filter
Lights - 152
Darks - 30
Flats - 30
Pre-Processing
Using my auto preprocessing scripts, with the following filters post registration:-
FWHM - 3.5
Weighted FWHM - 5
Roundness - 0.8
Out of the 152 images (5h4m ) this filtering lefts me with 107 (3h34m) lights. They were capture at 120s ISO800 using the Optolong L-Enhance filter.
This started out as being casually curious about the re-processing result so I did not "blink" the images I just used the filters as stated.
Stacked 107 * 2m -Total Integration Time = 3h34m
Post Processing (Nov 1, 2022)
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 (30,10,5)
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 and Curves - Loads of data on all 3 channels.
Raw - Highlights and Contrast
Raw - Texture - Minimal
Raw - Clarity - Moderate
Raw - Noise Reduction - minimal
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+(0.7*stars)).
Created JPG version for my Instagram and Twitter feeds.
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