NGC 7822 - Modified SHO palette

[Richard_]

My first narrowband image and first image from my QHY268M camera. Last week, we were very lucky to have such clear nights, where the air was still and not a cloud in the sky. NGC 7822 (a.k.a Sh2-171) resides in the constellation of Cepheus. It has hot, young stars and pillars and dust which is reminiscent of the "pillars of creation" from M16 The Eagle Nebula.

 

I love how this image has come out! The data was really easy to process thanks to the amazing IMX571 sensor. There's about 3.5hrs of SII data, 2hr of H data and 5.5hr of OIII data. All processing was performed in PixInsight. I used a modified hubble palette which is a 50/50 combination of traditional SHO palette with the ForaxX SHO palette.

 

Image acuisition details and processing information can be found below. Comments and criticism are welcome!

 

https://www.astrobin.com/ybm98t/

 

 

Acquisition Details

Camera: QHY268M (Readout Mode #1, Gain 56, Offset 25)

Telescope: WO FLT120 (with x0.8 reducer @ 624mm FL)

Mount: EQ6-R

Filters: Antlia EDGE 4.5nm (SHO)

Filterwheel: QHYCFW3-M-US

Focuser: Pegasus Focus Cube 2

Guidescope/camera: WO 50mm / ASI290MM

• S: 40 x 300s = 3h20m
• H: 24 x 300s = 2h
• O: 65 x 300s = 5h25m
• Total = 10h45m

Location: South Wales, UK (Bortle 5 in my garden 🙂 )

Imaging Dates: 27-Jul-2022  |  08-Aug-2022  |  09-Aug-2022  |  10-Aug-2022  |  13-Aug-2022

 

Darks: 30

Flats: 10

Bias: 100

Temperature: -5C

 

Processing Details

Calibration & Stacking

• All done in PixInsight
• Chuck all subs from multiple nights into WBPP script to calibrate
• Subframe selector, reject poor eccentricity and FWHM
• Normalised Scale Gradient
• Register and create master lights

Master Lights (S,H,O)

• Crop out stacking artifacts
• EZDeconvolution (using star masks made from StarNet2)
• NoiseXterminator
• Auto-stretch and apply with STF and Histogram transformation
• PixelMath combinations to create two images:
  • SHO palette (R=S, G=H, B=O)
  • ForaxX SHO palette 

  • // R:
    (O^~O)*S+~(O^~O)*H
    
    // G:
    ((O*H)^~(O*H))*H+~((O*H)^~(O*H))*O
    
    // B:
    O
    

     

  • Apply SCNR to SHO image
  • Invert SHO image, SCNR to remove magenta cast

Combination (some info can be found here on YouTube)

• PixelMath 50/50 combination of SHO and ForaxX SHO
• LRGB combination (i.e. add H-alpha as L data)
• Correct Magenta Stars
• Curves adjustment
• Local Histogram Equalisation
• DarkStructureEnhance
• EZ Star Reduction
• Unsharp mask (using mask to protect background)
• Save as PNG

Edited August 18, 2022 by Richard_
Added info

[Sunshine]

A beautiful image!

[Fegato]

Great image, well done - and nice to see another imager in South Wales!