Hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  Crescent Nebula  ·  NGC 6888  ·  Sh2-105
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Crescent Nebula (HOO), 



    
        

            Linda
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Getting plate-solving status, please wait...
Crescent Nebula (HOO), 



    
        

            Linda
Powered byPixInsight

Acquisition details

Dates:
July 14, 2021 ·  July 15, 2021 ·  July 16, 2021 ·  July 17, 2021 ·  July 24, 2021 ·  July 25, 2021 ·  July 28, 2021 ·  July 29, 2021 ·  July 30, 2021 ·  July 31, 2021 ·  Aug. 1, 2021 ·  Aug. 2, 2021 ·  Aug. 3, 2021
Frames:
Astrodon H-alpha 5nm: 56×900(14h) -20°C bin 1×1
Astrodon OIII 5nm: 74×900(18h 30′) -20°C bin 1×1
Integration:
32h 30′
Darks:
40
Flats:
50
Bias:
40
Avg. Moon age:
16.12 days
Avg. Moon phase:
53.23%

RA center: 20h11m41s.568

DEC center: +38°2532.12

Pixel scale: 0.727 arcsec/pixel

Orientation: 91.312 degrees (flipped)

Field radius: 0.542 degrees

More info:Open 

Resolution: 3806x3791

File size: 887.6 KB

Data source: Own remote observatory

Remote source: Sierra Remote Observatories

Description

I revisit this data to apply some newly learned techniques so this description applies to revision C.  The text after the line applies to revisions A & B.

I revisited this data with an eye towards applying some recently learned techniques.

Processing is a tad more complicated but it was worth it!

H and O masters:
dynamic crop
deconvolution
TGV Denoise (same as original processing to this point)
histogram transformation
clone each master and call them o_starless and h_starless

h_starless, o_starless
StarXterminator (clone the images as h_lum, o_lum)
TGV denoise

HOO:
channel combination (h_starless, o_starless, o_starless)
histogram transformation to balance color peaks
channel combination lum->L
pixel math in hoo_stars using star mask (max function)

lum:
pixel math (h_lum+o_lum)/2 to create new image lum
TGV Denoise
LHE (2 scales)
Adv Sharpening script

hoo_stars
channel combination (h, o, o)
spend 2 hours finding just the right star mask to apply to HOO

---------------------------------------------------------------------------------
The weather continues to be unfriendly to imaging at home but thankfully the system at SRO keeps on going.

These processing steps are for revisions A & B. For processing in revision C see it's description. 

Processing:
H-a
dynamic crop
deconvolution
tgv denoise

oIII
dynamic crop
deconvolution
tgv denoise
linear fit (to h-a)

HOO:
channel combination
histogram transformation
LHE
curves (contrast & color)
tgv Denise (chrominance only)
Adam block's star de-emphasis
Adv Sharpening

With LHE and the curves I used a GAME mask to affect the Crescent only.
Then I inverted that mask to bring down the background a bit to create some visual separation between the nebula and the background nebulosity.

Finally, in revision B, I used the color mask script to select the blue and then used range select to (mostly) get the OIII emission. I then binarized it to clean it up some and then used clone stamp to clean out some extraneous bits. With that mask in place I brought up the level some to enhance the OIII.

Comments

Revisions

  • Crescent Nebula (HOO), 



    
        

            Linda
    Original
  • Crescent Nebula (HOO), 



    
        

            Linda
    B
  • Final
    Crescent Nebula (HOO), 



    
        

            Linda
    C

B

Description: brought out the oIII a bit more

Uploaded: ...

C

Description: I revisited this data with an eye towards applying some recently learned techniques.

Processing is a tad more complicated but it was worth it!

H and O masters:
dynamic crop
deconvolution
TGV Denoise (same as original processing to this point)
histogram transformation
clone each master and call them o_starless and h_starless

h_starless, o_starless
StarXterminator (clone the images as h_lum, o_lum)
TGV denoise

HOO:
channel combination (h_starless, o_starless, o_starless)
histogram transformation to balance color peaks
channel combination lum->L
pixel math in hoo_stars using star mask (max function)

lum:
pixel math (h_lum+o_lum)/2 to create new image lum
TGV Denoise
LHE (2 scales)
Adv Sharpening script

hoo_stars
channel combination (h, o, o)
spend 2 hours finding just the right star mask to apply to HOO

Uploaded: ...

Sky plot

Sky plot

Histogram

Crescent Nebula (HOO), 



    
        

            Linda