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Contains:  IC 444, IC 443, The star μGem, The star Propus (ηGem), Part of the constellation Gemini (Gem)
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The Jellyfish Nebula (IC443) imaged in SHO

Technical card

Resolution: 4414x3300

Dates:Feb. 4, 2018

Frames:
Astrodon Ha 5nm: 283x300" (gain: 200.00) -20C bin 1x1
Astrodon OIII 3nm: 119x600" (gain: 200.00) -20C bin 1x1
Astrodon SII 3nm: 179x300" (gain: 200.00) -20C bin 1x1

Integration: 58.3 hours

Darks: ~64

Flats: ~32

Bias: ~200

Avg. Moon age: 19.07 days

Avg. Moon phase: 80.43%

Bortle Dark-Sky Scale: 7.00

Astrometry.net job: 2053010

RA center: 94.849 degrees

DEC center: 22.844 degrees

Pixel scale: 2.022 arcsec/pixel

Orientation: 0.452 degrees

Field radius: 1.548 degrees

Locations: 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 (Bortle 7)
Dates: 12/9/17, 12/10/17, 12/11/17, 12/13/17, 12/20/17, 1/12/18, 1/13/18, 1/14/18, 1/16/18, 1/30/18, 1/31/18, 2/4/18
Gain: 200 Offset: 50
Camera temp: -20C
SII: 179x300" Astrodon 3nm
Ha: 283x300" Astrodon 5nm
OIII: 119x600" Astrodon 3nm
Total integration time: 58hr 20min
64x darks per calibration (master from library)
32x flats per calibration
200x bias per calibration (master from library)

Preprocessing:
Batch PreProcessing script to generate calibrated images
StarAlignment
LocalNormalization (except OIII)
ImageIntegration (Linear Fit rejection)
DrizzleIntegration
DynamicCrop
DBE
LinearFit to SII

Duplicated all three masters. One set used for tonemap creation, and one set used for a synthetic Lum.

Preparing masters for the tonemap (all processes applied to each master individually):
TGV and MMT noise reduction (via Jon Rista's method)
Histogram Transformation x2 (linear -> non-linear)
Created a starmask and removed stars via MMT and MorphologicalTransformation
Further eliminated stars by bringing into Photoshop and using "Dust & Scratches"

Tonemap processing:
SHO masters assigned to RGB channels respectively to create a color image
HistogramTransformation
About 5 different curves adjustments (a and b channels) using ColorMask Script to target individual colors and adjust them to an aesthetically pleasing composition
SCNR green

L Processing:
Created a synthetic luminance with PixelMath using the following formula: Ha*0.7 + Oiii*0.2 + Sii*0.1
Deconvolution
HistogramTransformation x2 (linear -> non-linear)
ExponentialTransformation to push nebulosity
LHE
MMT for slight sharpening

Combined the Luminance with the Tonemap using LRGBCombination

Post-combination adjustments:
HistogramTransformation
CurvesTransformation for slight contrast
SCNR green
MorphologicalTransformation for slight star size reduction
DarkStructureEnhance Script
ACDNR for slight noise reduction
CurvesTransformation for slight saturation
Resampled to 50% for web posting

Comments

Author

ak_astro
Andrew Klinger
License: None (All rights reserved)
7927
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The Jellyfish Nebula (IC443) imaged in SHO, 





    
        

            Andrew Klinger