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Contains:  NGC 1999, M 43, NGC 1982, NGC 1977, NGC 1980, M 42, Great Nebula in Orion, NGC 1976, NGC 1975, NGC 1981, NGC 1973, The star 45Ori, The star ιOri, The star θ2Ori, The star θ1Ori, The star 42Ori
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M42 - The Great Orion Nebula and Dust, 





    
        

            David McGarvey
M42 - The Great Orion Nebula and Dust

M42 - The Great Orion Nebula and Dust

Technical card

Resolution: 1103x921

Dates:Jan. 3, 2019

Frames: 82x60"

Integration: 1.4 hours

Avg. Moon age: 27.16 days

Avg. Moon phase: 6.20%

Astrometry.net job: 2460113

RA center: 83.919 degrees

DEC center: -5.195 degrees

Pixel scale: 13.879 arcsec/pixel

Orientation: 11.443 degrees

Field radius: 2.770 degrees

Locations: Back Yard, Westover, Pennsylvania, United States

Data source: Backyard

Description

The Great Orion Nebula, Running Man Nebula, and surrounding dust. A personal best for me on these objects. First light for my Nikon D750. This camera is a huge improvement over my D3200 in terms of dark current, pattern noise, and amp glow - I look forward to capturing more DSOs! Captured from my back yard in Westover, PA on 1/3/19 - bortle class 4 skies.

**Equipment:**

* Nikon D750 (Stock)
* Nikkor 300mm f/2.8 AI-S ED lens
* f/2.8
* ISO 1600
* AstroTrac TT320X-AG - no guiding
* Induro CLT404L Tripod

**Acquisition:**

* 82 x 60" lights (82 mins. total integration time)
* additional subs for core detail - 3 x 20", 4 x 10", 8 x 4", 8 x 2", 8 x 1"
* 50 flats from archive

**Processing:**

*Lightroom/ACR (Raw file development):*

* imported raw .NEF files
* highlights -100
* adjusted tone curve for RGB channels to align black point
* blacks -10
* luminance noise reduction +15
* remove chromatic aberration
* magenta/blue/orange defringing
* export as 16-bit TIFs

*DeepSkyStacker:*

* import 16-bit TIFs
* added 50 flats from archive
* stacked with the kappa-sigma algorithm
* no background color calibration
* saved result as 32-bit floating point (rational) TIF with no DSS changes applied

*RawTherapee (For highlights reconstruction/recovery):*

* opened 32-bit TIF from DSS
* highlight reconstruction > color propagation
* exposure compensation -0.7
* highlight compression - 40
* highlight compression threshold - 0
* black - 0
* lightness - 0
* contrast - 70
* saturation - 0
* output as 32-bit floating point TIF

*RNC-Color-Stretch:*

* opened 32-bit TIF
* set power factor to 599/1/1
* color enhancement factor 1.0
* color correction off
* output as 16-bit PNG file

*Photoshop:*

* Convert PNG to TIF
* GradientXTerminator
* Crop
* HLVG plugin to remove green cast
* Purple Fringe Killer plugin applied selectively using mask
* Corrected oblong stars; select stars > apply offset filter > darken blend mode
* Created starless layer > stretched with curves to pull fainter dust forward
* Applied high pass filter to starless layer and blended
* Added luminosity layer; (copy image > LAB color > copy L channel > luminosity blend mode)
* various color balance, saturation, and contrast tweaks to taste
* save as PNG

Comments

Author

dmcgarvey
David McGarvey
License: None (All rights reserved)
1831
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M42 - The Great Orion Nebula and Dust, 





    
        

            David McGarvey