Cocoon Nebula (IC 5146), LDN 1042 and vdB147 in Cygnus

Cocoon Nebula (IC 5146), LDN 1042 and vdB147 in Cygnus

This photo was taken this past new moon in October 2020, and comprises of four hours worth of exposures. The cocoon nebula is the red emissions nebula and contains a small star cluster that’s forming in the middle. Surrounding the nebula is a dense molecular cloud of dust some of which reflects the blue glowing light of a bright nearby star.

8in f4.9 Newtonian Cooled Color Camera Bortle 4 skies 60x4min

Full Resolution


In this crop one can get a closer look at the emission nebula, the young star cluster that has formed within as well as the blue reflection nebula to the left.


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  • Orion 8in F4.9 1000mm Newtonian Reflector

    • Flocked / Primary mirror replaced due to turned-down-edge
  • Sky-Watcher F4 Aplanatic Coma Corrector

  • Astronomik’s L3 UV/IR Luminance Filter

  • Orion Atlas Pro

  • ASI071mc Pro cooled to -15C


  • Data Acquired using N.I.N.A and Guided with PHD2

Total integration time: 4hr 00min

All pre-processing and post-processing was done in PixInsight. Full details below.

The resulting image is a combination of the following steps:

  • Inspected all subs for bad images with Blink, discarding subs containing clouds

  • Calibrated all subs with their corresponding master flat and master dark and then debayered

  • Used sub-frame selector to weight all images based on the following weighting


-ApprovalExpression "FWHM<4.5 && Eccentricity<0.65"

-WeightingExpression "(5*(1-(FWHM-FWHMMin)/(FWHMMax-FWHMMin))

+ 15*(1-(Eccentricity-EccentricityMin)/(EccentricityMax-EccentricityMin))

+ 15*(SNRWeight-SNRWeightMin)/(SNRWeightMax-SNRWeightMin)

+ 20*(Stars-StarsMin)/(StarsMax-StarsMin))

+ 30"
  • Selected the best sub from sub-frame selector and blink to use as a reference frame for aligning and integration

  • Integrated with Adaptive Normalization using Generalized ESD Pixel Rejection

    Image Integration

[RGB Processing]

  • Remove unwanted background gradients caused by light pollution

    Background Extraction

  • Background Neutralization

    Background Neutralization

  • Color Calibration

    Color Calibration

  • Additional Background Extraction

    Additional Background Extraction

  • Even Working Space for all channels

    RGB Workingspace

  • Noise Reduction using TGV

    TGV Noise Reduction

  • Restore Color of saturated stars

    Restore Saturated Star Color

    Restore Saturated Star Color

  • ArcSinh Stretch

    ArcSinh Stretch

  • Masked Stretch

    Masked Stretch

  • Clip the Tail of the RGB histogram

    Clip Tail

  • Reduce stars with a contours based star mask

    Star Reduction

Final RGB Before Processing Luminance

[Luminance Processing]

  • A synthetic Luminance was created after the previous color calibration and setting the RGB Working Space previously mentioned

    Extract Luminance

  • Sharpen the Details using MMT and a mask

    Sharpen Details with MMT

  • Noise Reduction was done using TGVDenoise with a low contrast mask and an auto-stretched local support, SCNR to remove the green overcast and MMT with a very protective luminance mask as documented by Jon Rista

    TGV Noise Reduction

    MMT Noise Reduction

  • Initial Stretch using Masked Stretch

    Masked Stretch

  • Bring the tail of the black point

    Bring in the Tail of the Histogram

  • Additional Stretch using Masked Stretch

    Masked Stretch

  • Local Histogram Equalization

    Local Histogram Equalization

  • Reduce stars with a contours based star mask

    Star Reduction

Final Luminance before Combination

[Combination and Final Adjustments]

  • Luminance was combined with RGB using LRGBCombination

  • Enhance the blue reflection nebulas using a blue chrominance mask and curves, re-applying luminance after adjusting

  • Enhance the Red Emission nebula using a red chrominance mask and Local Histogram Equalization

  • Further reduce stars using a new contours based mask and morphological transformation

  • Sharpen star cores using deconvolution and a star mask

  • Curves to adjust the overall color tones

  • Additional noise reduction in the dark nebula regions

  • Further Sharpen star cores using Unsharp Mask and a star mask

  • Additional Local Histogram Equalization on the Red emission nebula

  • Final Curves adjustment to adjust tones

  • An ICC Profile was applied to enable Black Point Compensation

Constructive criticism is welcome. Let me know what you think! How can I improve?