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  1. Data Management
  2. DM-16386

Recent data using obs_decam retrieves incorrect wcs with butler.get("calexp_wcs")

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    Details

    • Type: Bug
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: afw
    • Labels:
      None
    • Story Points:
      4
    • Sprint:
      Arch 2018-11-05, Arch 2018-11-12
    • Team:
      Architecture

      Description

      While reviewing DM-16253 I re-processed DECam data through processCCD to test the metadata fix, but found that the reported wcs of the images was occasionally catastrophically wrong. The bug appears seemingly randomly when the fits header is read to create a wcs:

      for _i in range(40):
          wcs_test = butler_test.get('calexp_wcs', {'visit': 411735, 'ccdnum': 10})
          print(wcs_test.pixelToSky(-.5,-.5))
      (137.919516, -1.319873)
      (nan, nan)
      (137.919516, -1.319873)
      (138.379127, +87.701332)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (228.379127, -0.000000)
      (137.919516, -1.319873)
      (138.379127, +87.701332)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (138.379127, +87.701332)
      (137.919516, -1.319873)
      (228.379127, -0.000000)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (nan, nan)
      (138.379127, +87.701332)
      (318.379127, -87.701332)
      (nan, nan)
      (228.379127, -0.000000)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (137.919516, -1.319873)
      (228.379127, -0.000000)
      (137.919516, -1.319873)
      (228.379127, -0.000000)
      (228.379127, -0.000000)
      (nan, nan)
      (137.919516, -1.319873)
      

      The above values are random each time, and the order is not repeatable.

      If the full exposure is read in and the wcs is obtained from exposure.getWcs(), then it is correct each time. Also, the above command when run on data ingested in late January 2018 also produces correct results.

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              Assignee:
              tjenness Tim Jenness
              Reporter:
              sullivan Ian Sullivan
              Reviewers:
              Russell Owen
              Watchers:
              Ian Sullivan, Jim Bosch, John Parejko, John Swinbank, Meredith Rawls, Russell Owen, Tim Jenness
              Votes:
              0 Vote for this issue
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              7 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved:

                  Jenkins

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