| categories:Astrophotography

M45 (Pleiades) WIP

Work-in-progress of Pleiades (need more lights), but since we aren't supposed to get clear skies for a while, I decided to practice my Pixinsight on the collected data so far.

Outstanding issues that I'm working on

  • Doubled diffraction spikes? I checked, and this was present in the raw frames too, so it isn't a stacking/registration problem. I know the scope is a bit out of collimation (stars are oblong under short exposures). Likely a combination of poor focus, incorrect coma corrector spacing and collimation.

  • The blooming from the stars seems to wreck detail in the near vicinity.

  • It seems I've lost most of the color! There is very little color even if you crank up the saturation, mostly in the halos. I think my camera has a different bayer pattern than I expected, so the color was lost in debayering.


  • Orion f/4 8” Newtonian Astrograph
  • Atlas EQ-G
  • QHY8 OSC
  • SSAG + 50mm viewfinder modified into guide scope (aka duct-taped SSAG to it)


  • Sequence Generator Pro
  • PixInsight
  • EQmod


  • Bortle Zone: ~3
  • Average temp: 10° - 15° F
  • Lights: 18x400s
  • Darks: 20x400s
  • Bias: 80x0s
  • Flats: 80x0.005s


  1. BatchPreprocess (bias + overscan, dark, flat, light + VNG debayer)
  2. DrizzleIntegration (x2 with 0.9 drip)
  3. DBE
  4. BackgroundNeutralization
  5. SCNR for green
  6. ColorCalibration
  7. TGVDenoise
  8. ATrousWaveletTransform to suppress a bit of “grid” pattern from drizzle (oops)
  9. MaskedStretch
  10. HDRMultiscaleTransform (6 layers to help tone down blooming)
  11. HDRMultiscaleTransform (2 layers for small details)
  12. MorphologicalTransform with star mask to reduce stars a bit
  13. Curves
  14. Final Histogram to clip blacks a bit more
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