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Image Integration - Subtract Pedestals

Andrew Macica
in PixInsight
In PixInsight Image Integration there is a checkbox for "Subtract pedestals".  When bringing up the process it defaults to this option being enabled.  My inclination, when calibrating, is to uncheck this option.  When performing calibration, such as creating master biases, darks and flats is there a benefit to checking "Subtract pedestals",  Also when integrating my calibrated lights my inclination is to leave "Subtract pedestals" unchecked.  

My inclination is to handle handle the pedestal in the post processing.  

I checked the PixInsight release notes and did not find anything on this option.

Am I missing something?  I s there something I should be awaare of with this option?

Comments

  • BlockHeadBlockHead
    Hi Andy,

    I believe the option Subtract Pedestals only comes into effect IF you have a FITS Keyword "PEDESTAL" and it has a value. Some software programs that calibrate data (that you might get from a remote observatory... already calibrated) add a fixed Pedestal. So if you don't have the keyword..or you do and it is "0" then you are OK. PixInsight isn't going to add anything (and having it checked or unchecked doesn't matter). It really only matters if you have the keyword *and*t there is a value there. Then you have to decide if you want to subtract it. Assuming that it is the same for every frame... subtracting a constant doesn't change the data- but helps PixInsight set a baseline for a set of images. So I think just keeping it checked will take care of most situations.

    -the Blockhead
  • Andrew Macica
    Thank you.  That was very helpful.

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