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  1. Data Management
  2. DM-20201

Fix DECam rotator type and angle in metadata translator

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

      Description

      DECam 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).

      The diagram on this page should help figure out the correct on-sky rotation angle.

      http://www.ctio.noao.edu/noao/node/2250

      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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            jbosch Jim Bosch added a comment -

            on adding a new camera geom frame for this.  I do think it probably merits an RFC, in part because I don't actually know whether parity flip should go between FIELD_ANGLE and SKY or somewhere else.  That RFC might also be a good time to bring up the possibility of a new Cartesian plane between FOCAL_PLANE and FIELD_ANGLE (i.e. differing from FIELD_ANGLE only in a gnomonic projection and possibly units), which I suspect would make a lot of the WCS-from-camera-geometry work we're doing simpler.

            Show
            jbosch Jim Bosch added a comment - on adding a new camera geom frame for this.  I do think it probably merits an RFC, in part because I don't actually know whether parity flip should go between FIELD_ANGLE and SKY or somewhere else.  That RFC might also be a good time to bring up the possibility of a new Cartesian plane between FOCAL_PLANE and FIELD_ANGLE (i.e. differing from FIELD_ANGLE only in a gnomonic projection and possibly units), which I suspect would make a lot of the WCS-from-camera-geometry work we're doing simpler.
            Show
            Parejkoj John Parejko added a comment - Jenkins: https://ci.lsst.codes/blue/organizations/jenkins/stack-os-matrix/detail/stack-os-matrix/30024/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 DECam.

            Show
            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 DECam.
            Hide
            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, Eric Morganson, Jim Bosch, John Parejko, John Swinbank, Lauren MacArthur, Meredith Rawls, Merlin Fisher-Levine, Russell Owen, Tim Jenness
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                Updated:
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