PixInsight - Comet Processing

Automatic Weighted Batch Pre-processing for Comets

updated: 2023-02-12


This script will add all the light frames, the flats, the darks and the bias frames, register them, stack and debayer


Script 🡺 Batch Processing 🡺 WeightedBatchPreprocessing


Batch of original pre-selected Light frames + master Dark, Flats and Bias frames


batch of debayered and comet-aligned frames  with a *_a_c_d_r.xisf  suffix

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Perform a Automatic Selection using Sub-Frames Selector


Open the Automatic Weighted Batch Pre-processing Script


Set Global Options

  • CFA must be checked for color cameras; it will force a debayering of the images.
  • Optimize dark frames: will work on some DSLRs but probably not on OSC cameras.
  • Make sure to check Up-Bottom FITS for ZWO ASI294 (or final picture will be reversed!)

Figure 1.1


Adding Frames (Lights, Bias, Dark etc.)

If you want to use Master calibration frames instead of multiple single calibration frames, then make sure the file name of the master files start with "Master".

Make sure to check

Master frames will be marked with an asterisk, see figure 2.1 on the right

For example: if you did a live stacking with ASIAIR Pro you will get filenames like: "Stack20_Bias_1.0ms_Bin1_gain120_20210813-134241.fit".

Just rename them to e.g. "Master_Flat20_Config04_40.0ms_Bin1_gain120_20210813-144229.fit" and the automatic batch process will be able to treat them as master files. Otherwise the calibration frames will be ignored during the light frame calibration part of the process with an error message like:

*** Warning: Cannot integrate less than three frames.

!!! Error: Master Flat file was not be generated.

When adding light you may also consider adding the manually approved light frames from 1.1 Blink or 1.2 Automatic Selection using Subframe Selector in order to avoid integrating frames with satellite streaks or other artifacts.

Figure 2.1

Figure 2.2


Bias Frames Integration Settings

Combination: Average

Rejection Algorithm:

  • Up to 15 frames: use Sigma Clipping
  • Over 15 frames: use Winsorized Sigma Clipping

If you are using Master Bias Frame, the above settings do not apply. In this case use "No Rejection" as rejection algorithm.


Dark Frames Integration Settings

same settings apply as for Bias Frames


Flat Integration Settings

same settings apply as for Bias Frames


Light Frame Handling Subframe Weighting for Comets

Important: please uncheck the Image Integration step for comets, as the alignment will be done with a different tool: the Comet Alignment Tool (see next step)


Linear Pattern Subtraction


Cosmetic Correction


Subframe Weighting

SNR: If this option is checked light frames will be analyzed and weighted accordingly to the relative weights assigned to FWHM, eccentricity and SNR. Weights are saved into the image as WBPPWGHT header key which will be used during the ImageIntegration process.


Image Registration 

try the settings on the right.

Set Pixel Interpolation to Auto or try Lanczos-3, which seems to be a good interpolation algorithm.


Image Integration (Stacking)

Rejection Algorithm:

  • Up to 15 frames: use Sigma Clipping
  • Over 15 frames: use Winsorized Sigma Clipping.


On the Post-Calibration tab

enable Drizzle configuration (always for OSC cameras!)


Set the output folder

Use subfolder "...\_Astro\Observations\2023\20230208-193349_C-2022 E3_GÖ-MBR\Work" as output directory.


Start the batch process

by first running a diagnostic check and then the click on Run if the diagnostic didn't return any problems.


Check and save the log file for documentation

e.g. into a subfolder "logs" and name it according to major process settings, e.g. "AWBP_Lanczos-3_ ProcessLogger.txt" or similar.

Example log file


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