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  1. Data Management
  2. DM-6529

Investigate single frame processing astrometry failures/poor solutions on some HSC chip/visits.

    Details

    • Type: Story
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: meas_astrom, obs_subaru
    • Labels:
      None
    • Templates:
    • Story Points:
      6
    • Sprint:
      DRP F16-2
    • Team:
      Data Release Production

      Description

      The astrometric solution of some visit/ccd combinations for HSC data are failing or finding very poor solutions. This typically occurs for the outermost (highly fringed) ccds (e.g. 100..103, 95). I provide some sample output below.

      LSST bad fit: visit=19696 ccd=100

      processCcd.calibrate.astrometry.refObjLoader: Loaded 71 reference objects
      processCcd.calibrate.astrometry.matcher: filterStars purged 0 reference stars, leaving 71 stars
      processCcd.calibrate.astrometry.matcher: Purged 4436 unusable sources, leaving 288 usable sources
      processCcd.calibrate.astrometry.matcher: Matched 6 sources
      processCcd.calibrate.astrometry.matcher WARNING: Number of matches is smaller than request
      processCcd.calibrate.astrometry: Matched and fit WCS in 1 iterations; found 6 matches with scatter = 0.000 +- 0.000 arcsec
      

      HSC fit: visit=19696 ccd=100

      2016-06-10T17:13:54: processCcd.calibrate.astrometry: Found 80 catalog sources
      2016-06-10T17:13:54: processCcd.calibrate.astrometry: Matching to 119/148 good input sources
      2016-06-10T17:13:55: processCcd.calibrate.astrometry: Matched 20 sources
      2016-06-10T17:13:55: processCcd.calibrate.astrometry WARNING: Number of matches is smaller than request
      2016-06-10T17:13:55: processCcd.calibrate.astrometry: 20 astrometric matches for 100, 0_31
      2016-06-10T17:13:55: processCcd.calibrate.astrometry: Refitting WCS
      2016-06-10T17:13:55: processCcd.calibrate.astrometry: Astrometric scatter: 0.038076 arcsec (with non-linear terms, 20 matches, 0 rejected)
      

      LSST failed fit: visit=19696 ccd=103

      processCcd.calibrate.astrometry.refObjLoader: Loaded 68 reference objects
      processCcd.calibrate.astrometry.matcher: filterStars purged 0 reference stars, leaving 68 stars
      processCcd.calibrate.astrometry.matcher: Purged 2206 unusable sources, leaving 225 usable sources
      processCcd.calibrate.astrometry.matcher: Matched 4 sources
      processCcd.calibrate.astrometry.matcher WARNING: Number of matches is smaller than request
      processCcd FATAL: Failed on dataId={'taiObs': '2015-01-21', 'pointing': 1116, 'visit': 19696, 'dateObs': '2015-01-21', 'filter': 'HSC-I', 'field': 'SSP_UDEEP_COSMOS', 'ccd': 103, 'expTime': 300.0}: 
        File "src/sip/CreateWcsWithSip.cc", line 142, in lsst::meas::astrom::sip::CreateWcsWithSip<MatchT>::CreateWcsWithSip(const std::vector<_RealType>&, const lsst::afw::image::Wcs&, int, const lsst::afw::geom::Box2I&, int) [with MatchT = lsst::afw::table::Match<lsst::afw::table::SimpleRecord, lsst::afw::table::SourceRecord>]
          Number of matches less than requested sip order {0}
      lsst::pex::exceptions::LengthError: 'Number of matches less than requested sip order'
      

      HSC fit: visit=19696 ccd=103

      2016-06-10T17:20:11: processCcd.calibrate.astrometry: Found 84 catalog sources
      2016-06-10T17:20:11: processCcd.calibrate.astrometry: Matching to 137/162 good input sources
      2016-06-10T17:20:11: processCcd.calibrate.astrometry: Matched 19 sources
      2016-06-10T17:20:11: processCcd.calibrate.astrometry WARNING: Number of matches is smaller than request
      2016-06-10T17:20:11: processCcd.calibrate.astrometry: 19 astrometric matches for 103, 1_31
      2016-06-10T17:20:11: processCcd.calibrate.astrometry: Refitting WCS
      2016-06-10T17:20:11: processCcd.calibrate.astrometry: Astrometric scatter: 0.086131 arcsec (with non-linear terms, 18 matches, 1 rejected)
      

      Other failed visit/ccd combos:
      visit=19684 ccd=101
      visit=30488 ccd=95: RuntimeError: Unable to match sources

      This may simply be due to some threshold in the configs that is rejecting more stars on the LSST side, but this is not confirmed. Please investigate the cause of these failures.

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                • Assignee:
                  rearmstr Bob Armstrong
                  Reporter:
                  lauren Lauren MacArthur
                  Watchers:
                  Bob Armstrong, Dominique Boutigny, John Swinbank, Lauren MacArthur, Paul Price
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                    Updated:
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