PixInsight Image Solver Script Explained

A recent update to PixInsight provided major changes to the Photometric Color Calibration process (PCC) and added a new process called Spectrophotometric Color Calibration (SPCC).  Here’s what they look like:

What you’ll notice with the new Photometric Color Calibration process is that it no longer performs a plate solve for your images as part of the process to calibrating the broadband color in your images.  You’ll also discover that after you’ve aligned and integrated your images, the integrated image will not have a plate solve solution.  As a result, neither PCC nor SPCC will be able to process the image.  You will now need to add a step for your broadband image data tp get a plate solution - this will mean using the Image Solver script.

The Image Solver script is designed to plate solve an image.  To get it, go to Scripts > Image Analysis > Image Solver. 

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Here is the script:

The plate solution you’ll get with this process will provide each pixel in the image specific coordinates using the WCS system.  Use the active window containing the image you want to solve.  The process will use the FITS RA and Dec data of your image and date info, unless the file doesn’t have to or it is suspect.  You can always use the search button for the object in the image and use that data.  Next, make sure the image scale of the equipment used is correct.  It will show a resolution for the Image Scale, but I always check the “Focal distance” selection and input the focal distance of the telescope used in millimeters.   You should also check that the pixel size of the camera used is correct; if it isn’t, you’ll need to correct that as well.  

In the Model Parameters section, I check the Local XPSD Server selection and select the Gaia EDR3 (XPSD) catalog.  If you don’t have this catalog, you’ll need to download it to your system from the PixInsight website.  

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After looking everything over, hit the Ok button and away you go.  The script will iteratively run plate solutions until it can not improve on the most current iterative solution for the image.  When this happens, the script will write this solution into the FITS file.  From here, you should be able to successfully run PCC or SPCC.  More on that in a future post.

Stay safe and Clear skies….

Astro Image Credits:

Barnard 22 - Telescope Live 1-Click Observation Data, Processed using PixInsight by Reggie Jones - https://app.telescope.live/click-grab/all?target=B22