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Contains:  Crescent nebula, NGC 6888, NGC6888, Sh2-105
Getting plate-solving status, please wait...
NGC6888 - Crescent Nebula - OSC + Mono Luminance, 


            Jonathan W MacCollum
Powered byPixInsight

NGC6888 - Crescent Nebula - OSC + Mono Luminance

Technical card

Imaging telescopes or lenses:Orion 203/1000 f/4.9

Imaging cameras:ZWO ASI071MC ProZWO ASI183MM-pro

Mounts:Celestron CGEM

Guiding telescopes or lenses:ZWO OAG

Guiding cameras:ZWO ASI 178MM

Software:PixInsight PinInsight 1.8.5Isbeorn N.I.N.A.PHD 2

Filters:Hutech IDAS LPS D1 2"

Accessory:Skywatcher 2" Coma Corrector f/4

Dates:June 26, 2019June 27, 2019June 28, 2019

Hutech IDAS LPS D1 2": 60x120" (gain: 111.00) -10C bin 1x1
Hutech IDAS LPS D1 2": 224x120" (gain: 90.00) -10C bin 1x1

Integration: 9.5 hours

Darks: ~60

Flats: ~30

Flat darks: ~30

Avg. Moon age: 24.08 days

Avg. Moon phase: 30.25%

Bortle Dark-Sky Scale: 4.00 job: 2769953

RA center: 20h 11' 54"

DEC center: +38° 23' 10"

Pixel scale: 0.496 arcsec/pixel

Orientation: -3.843 degrees

Field radius: 0.451 degrees

Resolution: 5445x3637

Data source: Backyard


After a number of false starts with this target I finally have acquired sufficient data to take a stab at processing the Crescent Nebula. I spent seven different nights trying to image it, but ended up rulling out the first 4 nights when I discovered much better data was being acquired when my primary mirror was being heated up. The dew seemed to have formed a very thin layer on the nights where data was acquired early in the morning and the sharpness and contrast in the last few nights were leaps and bounds better.

The color data was provided by the asi071mc pro camera (0.97"/px) and bayer drizzled with 0.7 drop shrink and luminance data was provided by the asi183mm pro camera (0.5"/px.)

D1 - 224x120s with 071mc pro OSC (7.5 Hours)
D1 - 60x120s with 183mm pro Mono (2 hours)

Processing steps:

Luminance Data:
* Drizzle 60x2min D1 data with drop shrink of 0.7
* DBE to create L_Orig
* Deconvolution with regularization and no local support
* TGV and MMT Noise Reduction of L_Orig
* Use Starnet++ to create a star mask, and expand, convolve it until a mask sufficient for fixing ringing in the deconvolution image can be made
* Replace the ringing stars in deconvolution with L_Orig
* Combine Deconvolution and Noise Reduction image with a clipped / convolved luminance mask (high signal deconvolution and low signal noise reduction)
* Stretch with Masked Stretch

Color Data:
* CFA Drizzle 224x2min OSC data with drop shrink of 0.7
* Register with luminance for cropping/alignment
* DBE, Background Neutralization and Photometric Color Calibration
* TGV and MMT Noise Reduction
* HSV Repaired Separation
* Stretch with Histogram Stretch
* Shrink Stars with contours based mask and morphological transformation
* Desaturate the extra blue haze from the center-most bright star

Combine L+OSC with LRGB Combination
Adjust curves for contrast and saturation



Jonathan W MacCollum
License: Attribution-NoDerivs Creative Commons


  • NGC6888 - Crescent Nebula - OSC + Mono Luminance, 


            Jonathan W MacCollum
  • Final
    NGC6888 - Crescent Nebula - OSC + Mono Luminance, 


            Jonathan W MacCollum


Description: Fix bad edge caused by dithering

Sky plot

Sky plot


NGC6888 - Crescent Nebula - OSC + Mono Luminance, 


            Jonathan W MacCollum