Merge branch 'tickets/DM-44805'

python/lsst/meas/astrom/astrometry.py

@@ -277,7 +277,7 @@ def solve(self, exposure, sourceCat):
             result.stats = self._computeMatchStatsOnSky(result.matches)
             maxMatchDistance = result.stats.maxMatchDist.asArcseconds()
             distMean = result.stats.distMean.asArcseconds()
-            distStdDev = result.stats.distMean.asArcseconds()
+            distStdDev = result.stats.distStdDev.asArcseconds()
             self.log.info("Astrometric fit iteration %d: found %d matches with mean separation "
                           "= %0.3f +- %0.3f arcsec; max match distance = %0.3f arcsec.",
                           i, len(result.matches), distMean, distStdDev, maxMatchDistance)

tests/test_astrometryTask.py

@@ -92,6 +92,17 @@ def doTest(self, pixelsToTanPixels):
         # Test that the sources used in the fit are flagged in the catalog.
         self.assertEqual(sum(sourceCat["calib_astrometry_used"]), len(results.matches))
 
+        # The following tests that the measured mean astrometry offset is not
+        # equal to its standard deviation (within the default tolerances of
+        # double-precision epsilon).  While this condition is not strictly
+        # required to be true, in reality it would be highly unlikely and is
+        # certainly not the case for this test as configured.  The motivation
+        # for adding this check is that it would have caught a refactor that
+        # mistakenly set them both as the mean.
+        self.assertFloatsNotEqual(
+            self.exposure.metadata["SFM_ASTROM_OFFSET_MEAN"], self.exposure.metadata["SFM_ASTROM_OFFSET_STD"]
+        )
+
         srcCoordKey = afwTable.CoordKey(sourceCat.schema["coord"])
         refCoordKey = afwTable.CoordKey(results.refCat.schema["coord"])
         refCentroidKey = afwTable.Point2DKey(results.refCat.schema["centroid"])