Celestial hemisphere:  Northern  ·  Constellation: Cassiopeia (Cas)  ·  Contains:  NGC 457  ·  The star φCas
Owl Cluster, NGC 457, Jason Tackett
Owl Cluster, NGC 457
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Owl Cluster, NGC 457

Equipment

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Acquisition details

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Description

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Processing Workflow (PixInsight)

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Pre-processing

1. Calibrate light frames using darks, bias, flats

2. Integrate using Windsorized sigma clipping rejection.

Post-processing

1. Initial crop (Dynamic crop) .

2. Remove vertical banding which seems to appear in my ISO400 subs that are 30 seconds or less. Perhaps my darks aren’t quite the right temperature (CanonBandingRedctionScript).

3. Reduce background gradient (AutomaticBackgroundExtraction, subtraction).

4. Reduce background gradient and neutralize background (DynamicBackgroundExtraction, subtraction).

5. Neutralize background (BackgroundNeutralization).

6. Set white balance (ColorCalibration; use entire image since it is all stars).

7. Set luminance coefficients to 0.333333 for RGB channels (RGBWorkingSpace).

8. Reduce background noise (MultiscaleLinearTransform w/ luminance mask).

9. Non-linear stretch (MaskedStretch script; target median background 0.15).

10. Increase contrast (CurvesTransformation “s” curve).

11. Reduce green (SCNR w/mask targeting background).

12. Reduce chrominance noise (ACDNR to chrominance with luminance mask).

13. Increase color saturation (CurvesTransformation).

14. Reduce saturation artifact in brightest stars (InterchannelCurves, reference:saturation, target: c; w/mask selecting brightest stars).

15. Brighten stars slightly (CurvesTransformation).

16. Reduce slight red cast by lowering blackpoint of red channel, lower median background brightness to 0.1 (HistogramTransformation).

17. Reduce large scale chrominance noise in background (InterChannelCurves, reference: L, target: c, w/mask protecting stars)

18 Final Crop (DynamicCrop).

19. Set ICC profile to sRGB for web publishing (ICCProfileTransformation).

Comments

Sky plot

Sky plot

Histogram

Owl Cluster, NGC 457, Jason Tackett