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  1. Data Management
  2. DM-21241

Fix setting of boresight rotation angle for imsim data

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Details

    • Story
    • Status: Done
    • Resolution: Done
    • None
    • obs_lsst
    • None
    • 4
    • DRP F19-2, DRP F19-4
    • Data Release Production

    Description

      For individual obs packages, we are using "translators" to convert metadata from raw files into internally consistent conventions (as many telescopes have different sets of conventions and header naming).  Our convention for boresight rotation angle is:

      At boresightRotAngle = 0, the focal plane pixels are aligned:
      +x: E->W (-ve RA), +y: S->N (+ve Dec)
      

      (and see the documentation).

      Accordingly, the imsim translator in obs_lsst should reflect that:

      boresightRotAngle = 90 deg - ROTANGLE
      

      (where the ROTANGLE is the FITS card in the raw data).

      The reason data is currently being processed properly is due to a compensation (prior to the translator functionality) for this 90 deg shift in the lsstCamMapper here. This latter "correction" should be removed from there and accommodated in the imsim translator.

      This change will be validated by running a visit of DC2 data before and after and checking that we get consistent results.

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          Sounds good to me.  Thanks for the speedy review...merged to master.

          lauren Lauren MacArthur added a comment - Sounds good to me.  Thanks for the speedy review...merged to master.

          If the question is ROTANGLE vs. ROTANGZ, I don't believe phosim images ever have both. At some point the header card changed. I think they both needs to be treated the same way.

          krughoff Simon Krughoff (Inactive) added a comment - If the question is ROTANGLE vs. ROTANGZ, I don't believe phosim images ever have both. At some point the header card changed. I think they both needs to be treated the same way.

          Great, that answers one part of the question.  The other is “how should they be treated?”  I.e. does the angle that exists need the same

          boresightRotAngle = 90 deg - ROTANGLE(or ROTANGZ)
          

          conversion in its translator?

          lauren Lauren MacArthur added a comment - Great, that answers one part of the question.  The other is “how should they be treated?”  I.e. does the angle that exists need the same boresightRotAngle = 90 deg - ROTANGLE( or ROTANGZ) conversion in its translator?

          I believe that same correction needs to be made to both imsim and phosim translators. The DC1 dataset had both imsim and phosim data and were both using the same mapper, so I believe that correction should continue to be applied to both.

          krughoff Simon Krughoff (Inactive) added a comment - I believe that same correction needs to be made to both imsim and phosim translators. The DC1 dataset had both imsim and phosim data and were both using the same mapper, so I believe that correction should continue to be applied to both.
          jchiang James Chiang added a comment -

          I think this correct: both phosim and imsim get that angle from the rotSkyPos parameter in the instance catalogs that both currently use for simulating specific visits.

          jchiang James Chiang added a comment - I think this correct: both phosim and imsim get that angle from the rotSkyPos parameter in the instance catalogs that both currently use for simulating specific visits.

          People

            lauren Lauren MacArthur
            lauren Lauren MacArthur
            Tim Jenness
            Eli Rykoff, James Chiang, John Parejko, Lauren MacArthur, Robert Lupton, Simon Krughoff (Inactive), Tim Jenness, Yusra AlSayyad
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            Dates

              Created:
              Updated:
              Resolved:

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