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Lobster Claw (SHO), 



    
        

            Linda
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Lobster Claw (SHO)

Revision title: June 2023 reprocessing in SHO

Getting plate-solving status, please wait...
Lobster Claw (SHO), 



    
        

            Linda
Powered byPixInsight

Lobster Claw (SHO)

Revision title: June 2023 reprocessing in SHO

Acquisition details

Dates:
Oct. 5, 2021 ·  Oct. 6, 2021 ·  Oct. 7, 2021
Frames:
Astrodon H-alpha 3nm: 52×360(5h 12′) (gain: 56.00) -5°C bin 1×1
Astrodon OIII 3nm: 24×360(2h 24′) (gain: 56.00) -5°C bin 1×1
Astrodon SII 3nm: 46×360(4h 36′) (gain: 56.00) -5°C bin 1×1
Integration:
12h 12′
Darks:
50
Flats:
25
Flat darks:
50
Avg. Moon age:
9.88 days
Avg. Moon phase:
0.93%
Bortle Dark-Sky Scale:
4.00

RA center: 23h14m38s.77

DEC center: +60°1305.3

Pixel scale: 1.115 arcsec/pixel

Orientation: -90.288 degrees

Field radius: 1.164 degrees

WCS transformation: thin plate spline

More info:Open 

Resolution: 6252x4176

File size: 2.2 MB

Locations: Maurertown, Maurertown, VA, United States

Data source: Backyard

Description

A rare image form home this year. The clouds have been all but interminable this summer and fall and the clear nights were either marred by the smoke out west, 90+% humidity or the moon. But, beggars can't be choosers when it comes to clear skies at home.

This data was acquired between 25 Sep 2021 and 21 Oct 2021. The dates listed above are just in the middle of the range.  I ended up not using a good chunk of the data I collected thanks to sky issues (alas, Normalize Scale Gradient is a harsh mistress and said a good chunk of the dat was not up to snuff thanks to the aforementioned obstacles) and it it tedious to figure out exactly how many frames from each day got used. Despite the loss of data I'm fairly happy with this. 

I reprocessed this in June 2023 because I was never entirely happy with the way the colors ended up on the original. The source of the issue was the "patchy" nature of the data. The right quarter of the data was a very strong green hydrogen. The lower claw was a very strong blue oxygen and everything else was more mixed. Those two section stood out garishly. My original solution was to "push" the colors around to get something more pleasing but I was not especially happy with my result.

This time I opted to selectively reduce saturation on the problem areas until they visually matched the rest of the image more. Then I could use curves to boost color levels back up a bit overall and that seemed to work better. Also, the *Xterminators and GHS made for a better result. Here's what I did:

each S, H and O:
blurXterminator
starXterminator (extracting screened stars)
noiseXterminator
GHS (GHS, linear, GHS)

SHO:
channel combination (SHO)
GHS on each channel to align peaks(ish)
ColorSaturation to desaturate the garish blues and greens
LHE
Curves (brought up levels a tad)
Curves (increased color modestly)
MLT (mild sharpening)
pixel math in stars (screen)

stars:
I had experimented with a Foraxx palette but it turned out more garish than SHO, especially in the lower claw but the foraxx stars were quite nice so I used that combination for the stars android a mild unsharp mask on them.

Here's the processing for the original version:

S H and O masters:
starXterminator
histogram transformation
tgv denoise

SHO:
channel combination (SHO)
histogram transformation
LHE
MLT sharpening
curves contrast and hue
pixel math in stars

stars:
channel combination in the stars extracted by starxterminator
histogram transformation

I tried to keep a light touch on things like LHE and sharpening as they easily made a very chaotic nebula look over processed. Hopefully I stayed on the good side of that line. I did push the colors around with the hue control in curves as I wasn't especially happy with the look of the straight SHO combine

Comments

Revisions

  • Lobster Claw (SHO), 



    
        

            Linda
    Original
  • Final
    Lobster Claw (SHO), 



    
        

            Linda
    B

B

Title: June 2023 reprocessing in SHO

Description: see main text for details

Uploaded: ...

Sky plot

Sky plot

Histogram

Lobster Claw (SHO), 



    
        

            Linda