Celestial hemisphere:  Southern  ·  Constellation: Sagittarius (Sgr)  ·  Contains:  Checkmark Nebula  ·  Eagle Nebula  ·  IC 1283  ·  IC 1284  ·  IC 4701  ·  IC 4715  ·  Lobster Nebula  ·  M 16  ·  M 17  ·  M 23  ·  M 24  ·  NGC 6494  ·  NGC 6554  ·  NGC 6604  ·  NGC 6611  ·  NGC 6618  ·  Small Sgr Star Cloud  ·  Swan Nebula  ·  The star 15Sgr  ·  The star 16Sgr  ·  The star γSct  ·  The star μSgr  ·  omega Nebula
Eagle, Omega and the Sagittarius star cloud, stille
Eagle, Omega and the Sagittarius star cloud
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Eagle, Omega and the Sagittarius star cloud

Eagle, Omega and the Sagittarius star cloud, stille
Eagle, Omega and the Sagittarius star cloud
Powered byPixInsight

Eagle, Omega and the Sagittarius star cloud

Equipment

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Acquisition details

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Description

1 stack of 46 images, Canon 800D at ISO 800, Pentax 135mm f2.5 lens at f4, 30s exposures, tracked with Omegon minitrack lx2. a couple dozen darks, 120 biases. Processed in PixInsight as below

***** Integration

lightvortexastronomy tutorial (https://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html)

* CC defect list + master dark (sigma = 10)

* weighing:

15*(1-(FWHM-FWHMMin)/(FWHMMax-FWHMMin))

+ 25*(1-(Eccentricity-EccentricityMin)/(EccentricityMax-EccentricityMin))

+ 10*(SNRWeight-SNRWeightMin)/(SNRWeightMax-SNRWeightMin)

+ 30*(1-(Median-MedianMin)/(MedianMax-MedianMin))

+ 20

* img 2868 ref

* generalized student ESD rejection, remove range_low 0.2

***** Linear processing

* crop and rotate

* linearfit R and B channels to G, channel combine

* DBE 3, manually placed points

* color calibration, neutralizing background by upper right corner

* Denoised - EZDenoise, TGV decrease exponent by -1

*****Nonlinear processing

*** Initial stretch and corrections

* Ezsoftstretch, median 0.25

** Halo fixes

* blue_mask = sagittarius_B - (sagittarius_G + sagittarius_R)/2

* stretch blue mask shadows 0.04 mids 0.08

* with masks on, SNCR blue, SNCR green

* color calibration on background ref upper right (upper limit 0.22), structure detection w/ lower limit 0.6 and upper 0.9

*** Multilayer processing

http://www.stelleelettroniche.it/en/2014/09/astrophoto/m42-ngc1975-multilayer-processing-first-part/

** First iteration (detail)

* extract 4 MMT layers, diff,

* create mask: extract original luminance, stretched shadows 0.05 mids 0.35, turn starless, stretch further shadows 0.05 mids 0.3, apply on diff.

* s-shaped luminance curve, boost saturation heavily

* sum back together

** Second iteration (nebulas)

* extract 5 MMT layers, diff,

* create mask: extract original luminance, make starless, blur with 5 layers of MMT stretched shadows 0.05 mids 0.35, turn starless, stretch further shadows 0.05 mids 0.3 (sagittarius_L). Apply on diff

* create mask 2: from sagittarius_L, 1 - abs($T - 0.5) - sagittarius_mids

* s-shaped luminance curve, boost saturation heavily

* sum back together

** Third iteration (milky way)

* extract 5 MMT layers, diff,

* using sagittarius_mids on left, s-shaped luminance curve, boost saturation heavily

* sum back together

** Fourth iteration (major milky way)

* extract 8 MLT layers, diff

* mask with own luminance stretched mids 0.25 twice

* curve boost luminance, saturation

* with mask removed, desaturate blues

* pixelmath back together, normalized

*** With blue mask on, another iteration of SNCR blue and then green

**** Starless + stars processing

*** Starless:

* LHE 512, contrast 1.5, meld 2 * starless + lhe, normalized

* LHE 256, contrast 1.5, meld 4 * starless + lhe, normalized

*** Stars

* invert, SNCR green, invert again - fixes CA halos

* morphological transformation, erosion, 6x0.2

*** Finishers

* Reunite

* SNCR green

* MMT sharpen - 6 layers, biases 0.05 0.05 0.025 0.025 0.012 0.005

Comments

Sky plot

Sky plot

Histogram

Eagle, Omega and the Sagittarius star cloud, stille