Merge pull request #67 from lsst/tickets/DM-27547

DM-27547: warn about psfCandidates near edge

python/lsst/meas/extensions/psfex/psfexPsfDeterminer.py

@@ -285,8 +285,8 @@ def determinePsf(self, exposure, psfCandidateList, metadata=None, flagKey=None):
             try:
                 pstamp = psfCandidate.getMaskedImage(pixKernelSize, pixKernelSize).clone()
             except pexExcept.LengthError:
-                # Candidate is too close to the edge to get a stamp. Skip.
-                # TODO DM-27547: Replace with geometric condition
+                self.log.warning("Could not get stamp image for psfCandidate: %s with kernel size: %s",
+                                 psfCandidate, pixKernelSize)
                 continue
 
             # From this point, we're configuring the "sample" (PSFEx's version

tests/test_PsfexPsf.py

@@ -144,6 +144,10 @@ def setUp(self):
 
         xarr, yarr = [], []
 
+        # NOTE: Warning to those trying to add sources near the edges here:
+        # self.subtractStars() assumes that every source is able to have the
+        # psf subtracted. That's not possible for sources on the edge, so the
+        # chi2 calculation that is asserted on will be off.
         for x, y in [(20, 20), (60, 20),
                      (30, 35),
                      (50, 50),
@@ -181,7 +185,6 @@ def setUp(self):
         self.cellSet = afwMath.SpatialCellSet(bbox, 100)
 
         self.footprintSet = afwDetection.FootprintSet(self.mi, afwDetection.Threshold(100), "DETECTED")
-
         self.catalog = self.measure(self.footprintSet, self.exposure)
 
         for source in self.catalog: