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  1. Data Management
  2. DM-18400

Number of matches is smaller than request

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    • Story Points:
      4
    • Sprint:
      AP S19-5
    • Team:
      Alert Production

      Description

      Some CCDs in the HSC-RC2 reprocessing show this warning:

      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      

      This probably should be an error on the matcher, but it seems to be passed to the fitter and then report as a successful fit.

      A few data IDs of interest are visit=1872 ccd=11 visit=1868 ccd=13 visit=22648 ccd=4.

      The first CCD

      processCcd.calibrate.astromRefObjLoader INFO: Loaded 1580 reference objects
      processCcd.calibrate.astrometry.matcher INFO: Purged 661 sources, leaving 113 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 25 sources
      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      processCcd.calibrate.astrometry.matcher INFO: Purged 661 sources, leaving 113 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 1 sources
      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      processCcd.calibrate.astrometry INFO: Fit WCS iter 2 failed; using previous iteration: 
        File "src/sip/CreateWcsWithSip.cc", line 131, in lsst::meas::astrom::sip::CreateWcsWithSip<MatchT>::CreateWcsWithSip(const std::vector<T>&, const lsst::afw::geom::SkyWcs&, int, const lsst::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'
       
      processCcd.calibrate.astrometry INFO: Matched and fit WCS in 1 iterations; found 25 matches with scatter = 0.028 +- 0.019 arcsec
      

      The second

      processCcd.calibrate.astromRefObjLoader INFO: Loaded 1840 reference objects
      processCcd.calibrate.astrometry.matcher INFO: Purged 595 sources, leaving 133 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 27 sources
      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      processCcd.calibrate.astrometry.matcher INFO: Purged 595 sources, leaving 133 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 4 sources
      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      processCcd.calibrate.astrometry INFO: Fit WCS iter 2 failed; using previous iteration: All matches rejected in iteration 1
      processCcd.calibrate.astrometry INFO: Matched and fit WCS in 1 iterations; found 27 matches with scatter = 0.092 +- 0.049 arcsec
      

      And the third

      processCcd.calibrate.astromRefObjLoader INFO: Loaded 1441 reference objects
      processCcd.calibrate.astrometry.matcher INFO: Purged 1109 sources, leaving 99 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 47 sources
      processCcd.calibrate.astrometry.matcher INFO: Purged 1109 sources, leaving 99 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 49 sources
      processCcd.calibrate.astrometry.matcher INFO: Purged 1109 sources, leaving 99 good sources
      processCcd.calibrate.astrometry.matcher INFO: Matched 27 sources
      processCcd.calibrate.astrometry.matcher WARN: Number of matches is smaller than request
      processCcd.calibrate.astrometry INFO: Matched and fit WCS in 3 iterations; found 27 matches with scatter = 0.029 +- 0.020 arcsec
      

      The logs are from using the w_2019_10 stack. But the LengthError has appeared since w_2019_07, and the Number of matches is smaller than request warnings have been around for longer.

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                • Assignee:
                  cmorrison Chris Morrison
                  Reporter:
                  hchiang2 Hsin-Fang Chiang
                  Reviewers:
                  Colin Slater
                  Watchers:
                  Chris Morrison, Colin Slater, Hsin-Fang Chiang
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