As per my previous post on the Lion Nebula taken on 27th Sept 2022, it was obvious that I needed to bring in more data. I got the chance last night, October 17th 2022, a quarter moon spoilt the pretty black skies I had after about 2 hours but I scheduled the run in Nina for the full night hoping that the l-enhance filter and some background extraction during processing might give me the edge.
So what is it? Difficult to find lots of information. It's official title is SH2-132, it is a very faint emission nebula around 10,000 light years from us on the border of Cepheus and the Lacerta constellation.
15h36 Integration
Capture
Dust blower on Camera Sensor! - was starting to see some 'rings and spots' on the previous flats - Flats now seem good minor spots that might improve with a 'wet' clean of the sensor and optics but in my opinion not bad enough to risk this delicate cleaning operation.
2022-10-17 20:10 Started
Exposure at ISO800, 240s using the Optolong L-Enhance Filter
Lights - 140
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
With data from 2022-09-27 total 266 Lights 17h44m was registered.
Removed:-
f = 3.3
r=0.8
w=5
234 images remaining, visual blink but nothing to remove - minor aircraft trails I tend to let the averaging deal with as part of stacking.
Stacked 234 * 4m -Total Integration Time = 15h36m
Post Processing
As can be seen from the images compare to the single evenings exposures I took the image in a different direction this was made feasible simply due to more integration time. This is a faint target!
Siril
Crop - fairly minor to remove one corner of elongated stars and snip off the stacking artefacts
Rotate 180 - Lion upside down!
Background Gradient
Colour Calibration Photometry
Deconvolution, Kernal size of 0.8 used -this was critical, going above lead to doughnut artefacts which became very ugly when the starless image was generated
Asinh Stretch - 3 iterations with stitches of (100,30,2.5)
Histogram Stretch
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 - 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.
Created JPG version