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  1. Data Management
  2. DM-20188

Try out cameraGeom+boresight+rotation approach to initial WCSs


    • Type: Story
    • Status: Done
    • Resolution: Done
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      Alert Production


      We're hoping to start attaching improved initial WCSs using cameraGeom + boresight and rotation (DM-20154), but this depends on the quality of:

      • the cameraGeom models
      • the boresights from the raw headers
      • the rotation angles (when appropriate) from the headers

      Looking at the "easy" dataset Lauren MacArthur has been collecting, pick one full visit from each of (HSC, DECam, CFHT, LSST/DC2), and:

      • Process the data through at least CalibrateTask (so we can consider those fitted WCSs "truth", at least for now, because "easy" means we should be getting good fits).
      • For each detector, load the raw and apply the new function to create the from-raw WCS that John Parejko will provide as a Python snippet.
      • Compare the fitted WCS and from-raw WCS.  I recommend starting by looking at how the calexp bounding boxes transform onto the sky (the notebook attached to DM-19731 does this for HSC and may be useful as a starting point).  But looking at other points is of course fine, too, and would avoid some rotational degeneracies.

      We're interested in the following questions:

      • Does the from-raw WCS function not run at all for one of the cameras of interest, because:
        • the Visitinfo doesn't include boresight or rotation?
        • the cameraGeom lacks a coordinate system we need?
      • If the function appears to work but produces garbage, is it because:
        • the VisitInfo boresight values are bad?
        • the Visitinfo rotation values are bad (or perhaps inconsistently defined across cameras)?
        • the cameraGeom does not attempt to include optical distortion at all?
        • the cameraGeom has distortion, but it's not very good?
        • all of the above appear in order, but there's a scaling problem aligned with the zenith direction (i.e atmospheric refraction, which this model doesn't account for but perhaps could)?

      I think I already know that the answer for HSC will be "it appears to work but produces garbage because the cameraGeom distortion has a units problem".  It would be nice to hack something together to address that problem, in order to see if there are other problems, but I haven't thought much about how best to do that.


        1. DM-19731-CFHT.ipynb
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        2. DM-19731-DECam.ipynb
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        3. DM-19731-HSC.ipynb
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        4. DM-19731-LSST.ipynb
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        5. image.png
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        11. image-2019-06-24-17-03-42-808.png
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        13. image-2019-06-24-17-04-37-289.png
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        14. image-2019-06-24-17-05-04-227.png
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              • Assignee:
                cmorrison Chris Morrison
                jbosch Jim Bosch
                Chris Morrison, Jim Bosch, John Parejko, Lauren MacArthur, Tim Jenness
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