How to use dark/bias libraries with Pixinsight?

[mstriebeck]

Hi,

Just doing my first baby steps with preprocessing in Pixinsight (have used CCDStack so far). And I wonder how I can use dark/bias libraries with Pixinsight - especially with the BatchPreprocessing script. I have a directory structure:

<camera>\<Dark/Bias>\ - and then all the master files (different binning, different exposure time, usually the same temperature)

Is there some way that I can point Pixinsight to this directory and it will pick the correct bias and dark master frame depending on the data in the image (camera, binning, exposure time, temperature)?

Thanks
      MarkS

[bitli]

The BPP uses the Fits keywords for the image types (bias, dark, ...), the filter, the binning and the exposure time (it can also use the information from the EXIF and the name for raw files). Images of the same type/binning/filter/exposure (within some tolerance) are grouped together and a master is generated if required. The filter is only required to match flats.

BPP looks for the 'best' master dark when it needs one (it must be a dark with proper binning). It takes the one with the nearest exposure time (which can be quite different from the one you need, for example for flats if you do not have a flat dark). 

For flats the binning and filter must match.

So basically you can use a dark/bias library, but neither the camera nor the temperature are taken into account, so you should make sure that your library has a single bias/dark for a given binning/exposure.  You should also probably add a 'flat dark' (may be just copy a bias and alter the FITS keyword to have about the same exposure as the flat).

This is an overview and details should be looked up in the script.  Also check carefully the log generated by BPP, it will tell you which bias/dark is used.

--bitli