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Contains:  California nebula, NGC 1499, The star ξPer
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California Nebula (NGC1499) in HaRGB, 





    
        

            Andrew Klinger
California Nebula (NGC1499) in HaRGB

California Nebula (NGC1499) in HaRGB

Technical card

Resolution: 4384x3152

Dates:Nov. 18, 2017

Frames:
ZWO B 1.25": 12x180" (gain: 76.00) -20C bin 1x1
ZWO G 1.25": 14x180" (gain: 76.00) -20C bin 1x1
Ha 5nm: 101x180" (gain: 200.00) -20C bin 1x1
ZWO R 1.25": 13x180" (gain: 76.00) -20C bin 1x1

Integration: 7.0 hours

Darks: ~64

Flats: ~30

Bias: ~200

Avg. Moon age: 0.01 days

Avg. Moon phase: 0.00%

Bortle Dark-Sky Scale: 4.00

Astrometry.net job: 2052988

RA center: 60.186 degrees

DEC center: 36.371 degrees

Pixel scale: 2.017 arcsec/pixel

Orientation: 3.173 degrees

Field radius: 1.512 degrees

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

Data source: Unknown

Description

Equipment:
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

Software:
SGP
PHD2
CdC
PixInsight

Acquisition:
Location: Flower Mound, TX for Ha(Bortle 7), Atoka, OK for RGB(Bortle 3)
Dates: 10/1/17, 11/18/17
Gain: 200 Offset: 50 for Ha
Gain: 76 Offset: 15 for RGB
Camera temp: -20C
Ha: 101x180" Astrodon 5nm
R: 13x180"
G: 14x180"
B: 12x180"
Total integration time: 7hrs
64x darks per calibration
30x flats per calibration
200x bias per calibration

Preprocessing:
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
Using PixelMath, blended linear Ha with linear masters (50% into R, 10% into B, 5% into G)

Ha Processing:
Deconvolution
TGV & MMT noise reduction (via Jon Rista's method)
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).
HDRMulitiscaleTransform
LocalHistogramEqualization with inverted starmask
UnsharpMask slight sharpening
MorphologicalTransformation slight star reduction
CurvesTransformation slightly increase brightness
DarkStructureEnhance Script

RGB Processing:
Linear Fit to Red channel
ChannelCombination to create RGB
PhotometricColorCalibration
SCNR green
TGV and MMT noise reduction (via Jon Rista's method)
HistogramTransformation x2
SCNR green
CurvesTransformation for saturation

Combined Ha and RGB using the script HaRVB-AIP
SCNR green (darn green keeps coming back)
PixelMath with a StarMask to add the original RGB stars back into the image (they looked weird beforehand)
Resampled to 50% for web posting

Comments

Author

ak_astro
Andrew Klinger
License: None (All rights reserved)
1672
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California Nebula (NGC1499) in HaRGB, 





    
        

            Andrew Klinger