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  1. Data Management
  2. DM-22281

Adjust glossary definition of "PVI"


    • Type: Improvement
    • Status: To Do
    • Resolution: Unresolved
    • Fix Version/s: None
    • Component/s: lsst-texmf
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      In the glossary file, "PVI" is defined as "A fully-qualified LSST image from a single visit that includes the science pixel array and concomitant data including a quality mask and a variance array, in addition to a PSF characterization and metadata (including calibration metadata) about the image. It is stored with the background already subtracted"

      Leanne Guy included a near-verbatim subset of this, "A fully qualified LSST image from a single visit. It is stored with the background already subtracted." in a presentation that she asked me to read over.  I commented that it was hard to tell what "fully-qualified" was meant to convey, and that I thought it missed the key idea of "calibrated".  She referred me to the glossary definition, the source from which she had distilled the short version for her slides.

      My take on this is that "calexp"s are called "calexps" because "calibrated" is the key concept. I am happy to use the term "PVI" (and am not minded to reopen that discussion) but I think "calibrated" remains the central concept for explaining the significance of the term to a user.  It's not just that the image is dressed with lots of metadata that contain the calibration, but that the flux values and the WCS are directly usable as calibrated quantities.


      So, how about this:

      "A calibrated, background-subtracted image from a single visit, packaged with quality mask and variance arrays, as well as a PSF characterization, detailed calibration data, and other metadata about the image."?



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            • Assignee:
              gpdf Gregory Dubois-Felsmann
              Gregory Dubois-Felsmann, Leanne Guy, Tim Jenness
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