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Contains:  NGC 2239, NGC 2244, NGC 2252, Rosette nebula, The star 12Mon

Image of the day 03/13/2020

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    The Rosette Nebula (NGC2237) imaged in SHO, 



    
        

            Andrew Klinger
    The Rosette Nebula (NGC2237) imaged in SHO
    Powered byPixInsight

    The Rosette Nebula (NGC2237) imaged in SHO

    Technical card


    Dates:Jan. 6, 2020Feb. 26, 2020

    Frames:
    Ha 5nm: 168x300" (gain: 200.00) -20C bin 1x1
    Astrodon OIII 3nm: 48x600" (gain: 200.00) -20C bin 1x1
    Astrodon SII 3nm: 51x600" (gain: 200.00) -20C bin 1x1

    Integration: 30.5 hours

    Darks: ~64

    Flats: ~30

    Bias: ~200

    Avg. Moon age: 6.48 days

    Avg. Moon phase: 43.57%

    Bortle Dark-Sky Scale: 4.33


    Basic astrometry details

    Astrometry.net job: 3295053

    RA center: 6h 32' 37"

    DEC center: +5° 18' 21"

    Pixel scale: 3.373 arcsec/pixel

    Orientation: 274.313 degrees

    Field radius: 1.585 degrees


    Resolution: 2719x2016

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

    Data source: Backyard

    Description

    This false-color narrowband image shows the Hydrogen and Sulfur as warmer tones and Oxygen as blue.

    Equipment:
    OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)
    74mm aperture stop-down ring (brings scope to f/5.2)
    Mount: Orion Sirius EQ-G (HEQ-5)
    Guidescope: Orion 50mm guidescope
    Guiding camera: Orion StarShoot Autoguider
    Imaging camera: ZWO ASI1600MM-Cool

    Accessories:
    DeepSkyDad Autofocuser AF1
    QHYCCD PoleMaster

    Software:
    SGP
    PHD2
    CdC
    PixInsight

    Acquisition:
    Location: Flower Mound, TX (Bortle 7) for Ha, Atoka, OK (Bortle 3) for SII and OIII
    Dates: 1/6/20, 1/7/20, 2/26/20, 2/27/20, 2/28/20
    Gain: 200 Offset: 50
    Camera temp: -20C
    Ha: 168x300" Astrodon 5nm 1.25"
    SII: 51x600" Astrodon 3nm 1.25"
    OIII: 48x600" Astrodon 3nmn 1.25"
    Total integration time: 30hr 30min
    64x darks per calibration (master from library)
    30x flats per calibration
    200x bias per calibration (master from library)

    Preprocessing:
    Batch PreProcessing script to generate calibrated images
    StarAlignment
    ImageIntegration
    DrizzleIntegration
    DynamicCrop
    DBE

    Luminance Processing:
    Duplicated the master Ha to use as the luminance
    Deconvolution
    ArcsinhStretch and HistogramTransformation to bring to non-linear
    Created a duplicate starless version using StarNet++
    Combined the starless version with the image using PixelMath expression "F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)". (s=starless photo)
    LocalHistogramEqualization
    MultiscaleLinearTransform for sharpening
    CurvesTransformation
    MorphologicalTransformation for star size reduction
    UnsharpMask to harden up reduced stars

    Preparing separate Sii, Ha, and Oiii linear masters for tonemapping (applied to each master individually):
    TGV & MMT noise reduction (via Jon Rista's method)
    ArcsinhStretch and HistogramTransformation to bring to non-linear
    Removed stars via StarNet++
    Removed small artifacts by removing the first 3 layers via MMT
    LinearFit to Ha

    Combined prepared Sii, Ha, and Oiii masters with ChannelCombination:
    R: Sii
    G: Ha
    B: Oiii

    Tonemap Processing:
    HistogramTransformation to balance colors
    CurvesTransformation
    Invert>SCNR>Invert using a previously created magenta ColorMask to remove magentas
    CurvesTransformation using ColorMasks

    Combined Tonemap with Luminance using LRGBCombination:
    CurvesTransformation for slight contrast
    Resampled to 30% for web posting

    Comments

    Author

    ak_astro
    Andrew Klinger
    License: None (All rights reserved)
    114727
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    The Rosette Nebula (NGC2237) imaged in SHO, 



    
        

            Andrew Klinger

    In these public groups

    Narrowband imaging