The Question Mark

NGC 7822 – also known as the Question Mark nebula !

Equipment

  • Samyang 135mm f/2
  • QHY163M
  • Baader narrowband filters
  • Sky-Watcher HEQ5 Pro
  • QHY5L-II-C and QHY 30mm guidescope

Acquisition (Total : 18.5h)

  • Location : Backyard, bortle 5
  • Ha : 221x180s (11h)
  • OIII : 90x300s (7.5h)

Processing (PixInsight)

Individual channel processing

  • Gradient removal (DBE)
  • Deconvolution on Ha (tutorial)
  • Noise reduction (TGV and MMT)
  • HistogramTransformation

Color combination (tutorial)

  • StarNet++ on Ha and Oiii
  • Creating the dynamic factor
    • f : Oiii
      • Boosted using curves
  • Simulating the SII channel
    • Sii : Ha
      • Flattened using HDRMMT and curves
  • Combining the channels with PixelMath
    • R  : f*Sii + ~f*Ha
    • G : f*Ha + ~f*(.3*Sii+.7*Oiii)
    • B  : Oiii
  • Blending with a SCNR’d SHO image
    • f*SHO + ~f*Custom

Luminance processing

  • Protective stretch (tutorial coming soon)
  • Star reduction (tutorial)

LRGB processing

  • LRGBCombination
  • CurvesTransformation

Taken in November 2020

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