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Contains:  IC 435, NGC 2024, NGC 2023, Horsehead nebula, IC 434, IC 432, IC 431, The star Alnitak (ζOri), The star σOri
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Flame and Horsehead Nebula (IC434) in HaRGB, 


            Andrew Klinger
Flame and Horsehead Nebula (IC434) in HaRGB

Flame and Horsehead Nebula (IC434) in HaRGB

Technical card

Resolution: 4327x3100

Dates:Dec. 12, 2017

ZWO B 1.25": 26x180" (gain: 76.00) -20C bin 1x1
ZWO G 1.25": 22x180" (gain: 76.00) -20C bin 1x1
Astrodon Ha 5nm: 164x300" (gain: 200.00) -20C bin 1x1
ZWO R 1.25": 25x180" (gain: 76.00) -20C bin 1x1

Integration: 17.3 hours

Darks: ~64

Flats: ~30

Bias: ~200

Avg. Moon age: 24.26 days

Avg. Moon phase: 28.29%

Bortle Dark-Sky Scale: 4.00 job: 2053000

RA center: 85.002 degrees

DEC center: -2.596 degrees

Pixel scale: 2.023 arcsec/pixel

Orientation: 92.901 degrees

Field radius: 1.496 degrees

Locations: Atoka dark site, Atoka, Oklahoma, United States; Backyard, Flower Mound, Texas, United States

Data source: Unknown


OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)
Mount: Orion Sirius EQ-G (HEQ-5)
Guidescope: Orion 50mm guidescope
Guiding camera: Orion StarShoot Autoguider
Imaging camera: ZWO ASI1600MM-Cool


Location: Flower Mound, TX for Ha(Bortle 7), Atoka, OK for RGB(Bortle 3)
Dates: 10/23/17, 11/24/17, 12/8/17, 12/12/17
Gain: 200 Offset: 50 for Ha
Gain: 76 Offset: 15 for RGB
Camera temp: -20C
Ha: 164x300" Astrodon 5nm
R: 25x180"
G: 22x180"
B: 26x180"
Total integration time: 17hrs 19min
64x darks per calibration (master from library)
30x flats per calibration
200x bias per calibration (master from library)

Batch PreProcessing script to generate calibrated images
StarAlignment to register all frames to the reference
LocalNormalization of all registered frames (per channel)
ImageIntegration of each channel
DrizzleIntegration of each channel
DynamicCrop each master
DBE each master

Ha Processing:
HistogramTransformation x2
Duplicated the image to create a starless version, using a starmask and several iterations of MMT and MT. Then pushed the faint nebulosity in the starless version using PixelMath expression: "1-(1-$T)*(1-$T)"
Combined the starless version with the image using PixelMath expression "F=0.2; (1-(1-$T)*(1-s)*F)+($T*~F)" (s=starless photo).
LocalHistogramEqualization with inverted starmask
MLT for sharpening
HistogramTransformation to move black point in

RGB Processing:
Using PixelMath, blended linear Ha with linear masters (50% into R, 10% into B, 5% into G)
ChannelCombination to create RGB
SCNR green
TGV and MMT noise reduction (via Jon Rista's method)
HistogramTransformation x3

Combined Ha to RGB using LRGBCombination with Ha applied as a mask
HistogramTransformation to stretch image brighter
PixelMath with a StarMask to add the original RGB stars back into the image (they looked weird beforehand)
CurvesTransformation for a small stretch
SCNR green
CurvesTransformation for slight saturation
Resampled to 50% for web posting



Andrew Klinger
License: None (All rights reserved)

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Flame and Horsehead Nebula (IC434) in HaRGB, 


            Andrew Klinger