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Contains:  M 106, NGC 4258, NGC 4248, NGC 4232, NGC 4231
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Spiral Galaxy M106, 





    
        

            Jason Tackett
Spiral Galaxy M106

Spiral Galaxy M106

Technical card

Resolution: 3472x2268

Dates:March 31, 2014April 1, 2014

Frames:
UV/IR Cut 2": 61x55" ISO1600
UV/IR Cut 2": 53x75" ISO1600

Integration: 2.0 hours

Darks: ~89

Flats: ~30

Bias: ~54

Avg. Moon age: 1.29 days

Avg. Moon phase: 2.18%

Astrometry.net job: 277122

RA center: 184.721 degrees

DEC center: 47.294 degrees

Pixel scale: 1.234 arcsec/pixel

Orientation: -87.224 degrees

Field radius: 0.711 degrees

Locations: LaRC, Hampton, VA, United States

Description

M106 is a large spiral galaxy in the constellation Canes Venatici. A few smaller galaxies are also visible in the image. All subs were acquired at two locations in good old light-polluted Hampton, VA over the course of two nights with decent seeing. Post-processing is a mixture of techniques I learned from Alejandro Tombolini’s M106 tutorial and from Juan Carlos Moreno’s M109 tutorial which cites techniques by Manfred Schwarz and Gerald Wechselberger to reduce background noise (see references below). Thanks to those guys for posting such excellent information.

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Processing Workflow (PixInsight)
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Pre-processing
1. Calibrated light frames for all exposures averaged together using Linear Fit Clipping rejection to take into account variability in sky brightness between the two nights. (ImageIntegration)

Post-processing
1. Initial crop (Dynamic crop)
2. Reduce horizonal banding (CanonBandingReduction)
3. Reduce vertical banding (FastRotation, CanonBandingReduction, FastRotation)
4. Neutralize background (BackgroundNeutralization)
5. Reduce background gradient (AutomaticBackgroundExtraction; normalize, divide)
6. Reduce background gradient (AutomaticBackgroundExtraction; subtract)
7. Reduce background gradient (DynamicBackgroundExtraction; subtract)
8. Reduce background gradients (DynamicBackgroundExtraction; divide)
9. Neutralize background (BackgroundNeutralization)
10. Set white balance (ColorCalibration; use galaxy as white reference)

Luminance processing
11a. Extract luminance channel (ChannelExtraction)
11b. Reduce background noise (MultiscaleLinearTransform; target background)
11c. Reduce background noise (MultiscaleMedianTransform; target background)
11d. Reduce hot pixels (2x PixelMath [Schwarz script]; protect stars)
11e. Even out background (PixelMath [Wechselberger equation]; protect stars)
11f. Reduce dark pixels (3x PixelMath [Schwarz script]; protect stars)
11g. Deconvolution (Deconvolution; protect stars)
11h. Mild dynamic range stretch (HistogramTransformation)
11i. Stronger stretch (HistogramTransformation; protect bright stars)
11j. Lower black point (HistogramTransformation; protect bright stars)
11k. Compress dynamic range of galaxy (HDRMultiscaleTransform; target galaxy)
11l. Enhance local contrast in galaxy (LocalHistogramEqualization; target galaxy)
11m. Brighten galaxy (CurvesTransformation; protect stars)
11n. Reduce small scale noise in galaxy (MultiscaleMedianTransform; target galaxy)
11o. Reduce star sizes (MorphologicalTransformation; target stars)
11p. Slight noise reduction (MultiscaleLinearTransform; protect stars)

RGB processing
12a. Reduce background noise (MultiscaleLinearTransform; target background)
12b. Reduce background noise (MultiscaleMedianTransform; target background)
12c. Reduce hot pixels (2x PixelMath [Schwarz script]; protect stars)
12e. Even out background (PixelMath [Wechselberger equation]; protect stars)
12f. Reduce dark pixels (3x PixelMath [Schwarz script]; protect stars)
12g. Mild dynamic range stretch (HistogramTransformation)
12h. Stronger stretch (HistogramTransformation; protect bright stars)
12i. Lower black point (HistogramTransformation; protect bright stars)
12j. Strong color saturation (CurvesTransformation; protect stars)
12k. Chrominance noise reduction (ACDNR)
12l. More color saturation, including stars (CurvesTransformation; protect background)
12m. Reduce large scale chrominance noise in background (ATrousWaveletTransform; target chrominance; protect galaxy & stars)
12n. Reduce chrominance noise in background (2x InterChannelCurves; protect galaxy & stars)
12o. Increase star color saturation (CurvesTransformation; target stars)

LRGB processing
13. Combine RGB and luminance (LRGBCombination)
14. Remove green chrominance noise (SCNR)
15. Increase star color saturation (ColorSaturation; target stars)
16. Mild sharpening (MultiscaleMedianTransform; protect background)
17. Reduce background level and mild contrast enchance (CurvesTransformation)

References:
Alejandro Tombolini’s M106 tutorial:
http://www.pixinsight.com.ar/en/info/processing-examples/21/messier-106.html
Juan Carlos Moreno’s M109 tutorial:
http://astrofotourbana.blogspot.com.es/2014/04/m109-procesado-de-una-galaxia-en.html
Manfred Schwarz’ galaxy tutorial:
http://www.astrophoto.at/PixInsight/
Gerald Wechselberger’s PixInsight tutorials:
http://www.werbeagentur.org/oldwexi/PixInsight/PixInsight.html

Comments

Author

jtackett
Jason Tackett
License: Attribution Creative Commons
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Spiral Galaxy M106, 





    
        

            Jason Tackett

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