M45 - The Pleiades

Messier 45, the Pleiades, or "Seven Sisters" is one of the most recognizable objects in the Northern Hemisphere fall sky. Easily visible from heavily light polluted areas, M45 is a bright reflection nebula with lots of dust tendrils coming off in all directions.

 

This was a super quick 1/2 night project that I imaged this new moon.

 

- Location: Remote Observatory (Bortle 1, SQM 21.99) near Fort Davis, TX

- Total Exposure Time: 6.65 Hours

 

Equipment:

- Scope: Esprit 100ED w/ 1x Flattener

- Imaging Camera: QHY 268M

- Filters: Chroma LRGB (36mm)

- Mount: Astro Physics Mach1GTO

- Guidescope: SVBony 50mm Guidescope

- Guide camera: ASI 120mm mini

- Focuser: Moonlite Nitecrawler WR35

- Accessories: Pegasus Ultimate Powerbox v2, QHY Polemaster, Optec Alnitak Flip Flat

 

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Software:

- N.I.N.A for image acquisition, platesolving, and framing

- PHD2 for guiding

- PixInsight for processing

 

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Acquisition:

- L: 66 x 3m

- R: 22 x 3m

- G: 22 x 3m

- B: 21 x 3m

- All images at Gain 56, Offset 25 (Readout mode 1) and -5C sensor temperature

- 20 flats per filter

- Master Dark, Flat & Bias from Library

- Nights: 10/26/22

 

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Processing:

 

- WBPP for Pre-processing

- ImageIntegration for stacking

 

RGB Processing (Apply to each master then combine):

- DynamicCrop

- MureDenoise

- DynamicBackgroundExtraction

- StarAlign B and G to R

- ChannelCombination to combine into linear color image

- StarAlign to luminance

- StarXterminator on copy to create starless and extract stars. Save stars_only for later

- HT for stretch

- NoiseXterminator for slight noise reduction

- SCNR to remove green tint

- ColorMask to target green areas of reflection

- CurvesTransformation with ColorMask applied to remove green reflections

- ColorSaturation to saturate blues

- CurvesTransformation for further saturation

 

Luminance Processing:

- DynamicCrop

- MureDenoise

- DynamicBackgroundExtraction

- StarXterminator on copy to create starless version and extract lum_stars. Save lum stars

- GeneralizedHyperbolicStretch for initial stretch

- HistogramTransformation x2 for further stretch

- Slight UnsharpMask for sharpness

 

Combine Lum and RGB:

- LRGBCombination with chrominance NR enabled

- HistogramTransformation for green

- Invert -> SCNR -> Invert to remove magenta hue

- MultiscaleMedianTransform x2 with stretched luminance mask for chrominance noise reduction

- Slight NoiseXterminator for NR

- ColorSaturation for additional blue saturation

 

Add Stars Into Image and Further Processing:

- HistogramTransformation x3 on RGB stars to stretch

- Invert -> SCNR Green -> Invert to remove magenta on stars

- HistogramTransformation to bring nebula and stars_only images to pseudo-linear state

- PixelMath to combine stars and starless images

- HistogramTransformation to return to "stretched" state

- Extract luminance from stars_only and apply as star_mask

- Slight MorphologicalTransformation to reduce star emphasis

- NoiseXterminator for slight noise reduction

Done