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  1. Data Management
  2. DM-20202

Fix CFHT MegaPrime rotator type and angle in metadata translator

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    • Story Points:
      2
    • Epic Link:
    • Sprint:
      AP F19-1
    • Team:
      Alert Production

      Description

      CFHT MegaPrime has its rotator angle set to NaN in astro_metadata_translator, and its rotator type to UNKNOWN. Since it is on an equatorial telescope, we can just pre-compute the correct value, set rotType=SKY and set those in the translator and they will be correct for everything (or at least correct enough to provide an initial guess).

      There are diagrams on this page that may help figure out the correct on-sky rotation angle, though it's not as helpful as the DECam diagrams:

      https://www.cfht.hawaii.edu/Instruments/Imaging/Megacam/specsinformation.html

      One open question is whether we need to set a rotatorHandedness (when +Y is north, is +X is east or west?) value in VisitInfo, or whether we can easily get that from the camera geometry. At present, VisitInfo does not preserve this information, because Russell Owen assumed it would be managed by the camera geometry.

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            Parejkoj John Parejko added a comment -

            Based on suggestions from Lauren MacArthur, it does appear that CFHT MegaPrime uses +Y=N, +X=E, per an image in the document linked above and a line on this table:

            https://www.cfht.hawaii.edu/Instruments/Imaging/Megacam/generalinformation.html

            This does mean it has a handedness flip from DECam. Joy.

            Show
            Parejkoj John Parejko added a comment - Based on suggestions from Lauren MacArthur , it does appear that CFHT MegaPrime uses +Y=N, +X=E, per an image in the document linked above and a line on this table: https://www.cfht.hawaii.edu/Instruments/Imaging/Megacam/generalinformation.html This does mean it has a handedness flip from DECam. Joy.
            Show
            Parejkoj John Parejko added a comment - - edited Jenkins run: https://ci.lsst.codes/blue/organizations/jenkins/stack-os-matrix/detail/stack-os-matrix/30027/pipeline
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            Parejkoj John Parejko added a comment -

            Merlin Fisher-Levine: Two small PRs here, with what appear (from mucking with images in jupyter) to be the correct instrument angle for CFHT MegaPrime.

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            Parejkoj John Parejko added a comment - Merlin Fisher-Levine : Two small PRs here, with what appear (from mucking with images in jupyter) to be the correct instrument angle for CFHT MegaPrime.
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            mfisherlevine Merlin Fisher-Levine added a comment -

            Looks good.

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            mfisherlevine Merlin Fisher-Levine added a comment - Looks good.
            Hide
            Parejkoj John Parejko added a comment -

            Thanks for the speedy review.

            Merged and done.

            Show
            Parejkoj John Parejko added a comment - Thanks for the speedy review. Merged and done.

              People

              Assignee:
              Parejkoj John Parejko
              Reporter:
              Parejkoj John Parejko
              Reviewers:
              Merlin Fisher-Levine
              Watchers:
              Chris Morrison, Colin Slater, Dominique Boutigny, Jim Bosch, John Parejko, John Swinbank, Lauren MacArthur, Merlin Fisher-Levine, Tim Jenness
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              0 Vote for this issue
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              9 Start watching this issue

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                Updated:
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