Merge pull request #23 from lsst/tickets/DM-33446

DM-33446: Use TraceRadius in GAaP plugin
lsst · Feb 8, 2022 · 4777abc · 4777abc
2 parents 3ff5e6c + adfaec9
commit 4777abc
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/python/lsst/meas/extensions/gaap/_gaap.py b/python/lsst/meas/extensions/gaap/_gaap.py
@@ -551,8 +551,14 @@ def _gaussianizeAndMeasure(self, measRecord: lsst.afw.table.SourceRecord,
             raise measBase.FatalAlgorithmError("No PSF in exposure")
         wcs = exposure.getWcs()
 
-        psfSigma = psf.computeShape(center).getDeterminantRadius()
-        errorCollection = dict()
+        psfSigma = psf.computeShape(center).getTraceRadius()
+        if not (psfSigma > 0):  # This captures NaN and negative values.
+            errorCollection = {str(scalingFactor): measBase.MeasurementError("PSF size could not be measured")
+                               for scalingFactor in self.config.scalingFactor}
+            raise GaapConvolutionError(errorCollection)
+        else:
+            errorCollection = dict()
+
         for scalingFactor in self.config.scalingFactors:
             targetSigma = scalingFactor*psfSigma
             # If this target PSF is bound to fail for all apertures,

diff --git a/python/lsst/meas/extensions/gaap/_gaussianizePsf.py b/python/lsst/meas/extensions/gaap/_gaussianizePsf.py
@@ -118,7 +118,7 @@ def run(self, exposure: lsst.afw.image.Exposure, center: lsst.geom.Point2D,  # n
         result = self._buildCellSet(exposure, center, targetPsfModel)
         kernelCellSet = result.kernelCellSet
         targetPsfModel = result.targetPsfModel
-        fwhmScience = exposure.getPsf().computeShape(center).getDeterminantRadius()*sigma2fwhm
+        fwhmScience = exposure.getPsf().computeShape(center).getTraceRadius()*sigma2fwhm
         fwhmModel = targetPsfModel.getSigma()*sigma2fwhm  # This works only because it is a `GaussianPsf`.
         self.log.debug("Ratio of GAaP model to science PSF = %f", fwhmModel/fwhmScience)