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  1. Data Management
  2. DM-28224

The mjd and frac_mjd values in MT rotator (and hexapod?) headers are incorrect

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      Description

      The low-level MT rotator controller publishes telemetry and configuration messages with a header that include 4 fields describing time: mjd, frac_mjd, tv_sec and tv_nsec. The latter two appear to be correct, but mjd and mjd_frac (which should be the integer and fractional parts of UTC in MJD days) are actually just a "restatement" of tv_sec and tv_nsec (mjd = tv_sec and frac_mjd = tv_nsec/1e9).

      This issue is likely present in the low-level MT Hexapod controller, as well.

      Please do something about this. Three solutions that come to mind:

      • Delete the mjd and frac_mjd fields. This requires coordinated (but trivial) updates to ts_mtrotator (and ts_mthexapod), which requires some care. I am certainly happy to update the ts_mt... packages. It may also require updating the EUIs.
      • Fix the values. This is fairly easy to do and gives good backward compatibility (at least for ts_mtrotator and ts_mthexapod). I don't know what it does to EUI displays. We have no need for the data, but it avoids the need for a coordinate update to ts_mt... packages.
      • Leave the values alone but rename them to something more sensible. Given the needless duplication between mdj and tv_sec, this is by far my least favorite option.

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            ttsai Te-Wei Tsai added a comment - - edited

            After the discussion with Russell, we had the consensus to go the option 1.

            Removed the mjd and mjd_frac from telemetryHeaderStructure_t in ts_rotator_controller.
            Removed the mjd and mjd_frac from telemetryHeaderStructure_t in ts_hexapod_controller.

            Show
            ttsai Te-Wei Tsai added a comment - - edited After the discussion with Russell, we had the consensus to go the option 1. Removed the mjd and mjd_frac from telemetryHeaderStructure_t in ts_rotator_controller . Removed the mjd and mjd_frac from telemetryHeaderStructure_t in ts_hexapod_controller .
            Hide
            ttsai Te-Wei Tsai added a comment -

            Updated the frame size in ts_hexapod_gui.

            Show
            ttsai Te-Wei Tsai added a comment - Updated the frame size in ts_hexapod_gui .
            Hide
            ttsai Te-Wei Tsai added a comment -

            Updated the frame size in ts_rotator_gui.

            Show
            ttsai Te-Wei Tsai added a comment - Updated the frame size in  ts_rotator_gui .
            Show
            ttsai Te-Wei Tsai added a comment - Please help to review the following PRs: 1. https://github.com/lsst-ts/ts_rotator_controller/pull/16 2. https://github.com/lsst-ts/ts_hexapod_controller/pull/11 3. https://github.com/lsst-ts/ts_rotator_gui/pull/7 4. https://github.com/lsst-ts/ts_hexapod_gui/pull/7 Thanks!
            Hide
            rowen Russell Owen added a comment -

            Reviewed on github. Looks great. Thank you very much for making this simplification and eliminating the confusion of the mjd field that wasn't MJD.

            Show
            rowen Russell Owen added a comment - Reviewed on github. Looks great. Thank you very much for making this simplification and eliminating the confusion of the mjd field that wasn't MJD.

              People

              Assignee:
              ttsai Te-Wei Tsai
              Reporter:
              rowen Russell Owen
              Reviewers:
              Russell Owen
              Watchers:
              Russell Owen, Te-Wei Tsai
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