Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  27 b01 Cyg  ·  B147  ·  NGC 6871  ·  The star 27Cyg
NGC 6871 and Biurakan 2 - Open Clusters under a bright moon, Jonathan W MacCollum
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NGC 6871 and Biurakan 2 - Open Clusters under a bright moon

NGC 6871 and Biurakan 2 - Open Clusters under a bright moon, Jonathan W MacCollum
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NGC 6871 and Biurakan 2 - Open Clusters under a bright moon

Equipment

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Acquisition details

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Description

NGC 6871 and Biurakan 2 - Open Clusters under a bright moon

Spent some time bouncing around a few summer-time open clusters on the only clear night available to me last week. Was pleasantly surprised to see some nebulosity show up in those targets in the direction of the milky way despite the presence of the bright moon. I am really considering trying for some narrowband of this region in the future when I get the chance.

Enjoy, and feel free to share your thoughts and criticism. I never want to stop learning and improving!

Acquisition and Pre-Processing:

* Best 81 (of 141 total) x30s Lights weighted using the following subframe expression:

(10*(1-(FWHM-FWHMMin)/(FWHMMax-FWHMMin))

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

+ 25*(SNRWeight-SNRWeightMin)/(SNRWeightMax-SNRWeightMin))

+ 50

* Stacked with Linear Fit Clipping and CFA Drizzle 1x with 0.7 drop shrink

Color Calibration:

* DBE -> Background Neutralization -> Color Calibration -> Photometric Color Calibration

* Assign RGB Working space to 1,1,1

Luminance Processing:

* Extract Synthetic Luminance

* Subtle Sharpening with MMT and a Starmask (created by a stretched copy |> starnet++ |> convolution)

* TGV with a low contrast mask and strong edge protection

* MMT noise reduction with a high protective luminance mask

* Masked Stretch and Curves

RGB Processing:

* TGV with a low contrast mask and strong edge protection

* MMT noise reduction with a high protective luminance mask

* HSV Repaired Separation Script

* Additional round of DBE to eliminate a lingering moon gradient

* Histogram and Arcsinh Stretch to non-linear

Combine RGB and L

* StarNet++ to Separate Starless (and Orig-Starless to create StarsOnly)

* Starless: Curves to boost saturation and contrast on background -> ACDNR on small scale noise)

* Stars Only: Curves to tweak saturation and shift the hues to bring out the blue stars

* Recombine Stars and Starless with pixel math Starless+StarsOnly)

Final Touches:

* Chrominance noise reduction on the brighter stars to eliminate artifacts left behind by Starnet++

* Final round of Curves to back off the background where the signal is lacking

Comments

Sky plot

Sky plot

Histogram

NGC 6871 and Biurakan 2 - Open Clusters under a bright moon, Jonathan W MacCollum

In these public groups

ASI 071 mcc
Cooled Color Cams