Merge pull request #222 from lsst/tickets/DM-42024

DM-42024: Allow for low gains and allow initial outlier cutoff to have units of electrons.
lsst · Dec 6, 2023 · 2f39c65 · 2f39c65
2 parents 83e0762 + c0e6461
commit 2f39c65
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Showing 2 changed files with 27 additions and 6 deletions.
diff --git a/python/lsst/cp/pipe/ptc/cpSolvePtcTask.py b/python/lsst/cp/pipe/ptc/cpSolvePtcTask.py
@@ -139,8 +139,17 @@ class PhotonTransferCurveSolveConfig(pipeBase.PipelineTaskConfig,
     maxSignalInitialPtcOutlierFit = pexConfig.Field(
         dtype=float,
         doc="Maximum signal considered for intial outlier fit. This should be below "
-            "the PTC turnoff to ensure accurate outlier rejection.",
-        default=30_000.,
+            "the PTC turnoff to ensure accurate outlier rejection. If "
+            "scaleMaxSignalInitialPtcOutlierFit=True then the units are electrons; "
+            "otherwise ADU.",
+        default=50_0000.,
+    )
+    scaleMaxSignalInitialPtcOutlierFit = pexConfig.Field(
+        dtype=bool,
+        doc="Scale maxSignalInitialPtcOutlierFit by approximate gain?  If yes then "
+            "maxSignalInitialPtcOutlierFit is assumed to have units of electrons, "
+            "otherwise ADU.",
+        default=True,
     )
     minVarPivotSearch = pexConfig.Field(
         dtype=float,
@@ -1005,8 +1014,8 @@ def errFunc(p, x, y):
                 if self.config.binSize > 1:
                     bounds = self._boundsForAstier(parsIniPtc)
                 else:
-                    bounds = self._boundsForAstier(parsIniPtc, lowers=[-1e-4, 0.5, -2000],
-                                                   uppers=[1e-4, 2.5, 2000])
+                    bounds = self._boundsForAstier(parsIniPtc, lowers=[-1e-4, 0.1, -2000],
+                                                   uppers=[1e-4, 10.0, 2000])
             if ptcFitType == 'POLYNOMIAL':
                 ptcFunc = funcPolynomial
                 parsIniPtc = self._initialParsForPolynomial(self.config.polynomialFitDegree + 1)
@@ -1022,6 +1031,18 @@ def errFunc(p, x, y):
             # This algorithm was initially developed by Seth Digel for
             # the EO Testing pipeline.
 
+            if self.config.scaleMaxSignalInitialPtcOutlierFit:
+                approxGain = np.nanmedian(meanVecOriginal/varVecOriginal)
+                maxADUInitialPtcOutlierFit = self.config.maxSignalInitialPtcOutlierFit/approxGain
+                self.log.info(
+                    "Using approximate gain %.3f and ADU signal cutoff of %.1f for amplifier %s",
+                    approxGain,
+                    maxADUInitialPtcOutlierFit,
+                    ampName,
+                )
+            else:
+                maxADUInitialPtcOutlierFit = self.config.maxSignalInitialPtcOutlierFit
+
             if maxIterationsPtcOutliers == 0:
                 # We are not doing any outlier rejection here, but we do want
                 # an initial fit.
@@ -1034,7 +1055,7 @@ def errFunc(p, x, y):
                 pars = res.x
                 newMask = mask.copy()
             else:
-                newMask = (mask & (meanVecOriginal <= self.config.maxSignalInitialPtcOutlierFit))
+                newMask = (mask & (meanVecOriginal <= maxADUInitialPtcOutlierFit))
 
                 count = 0
                 lastMask = mask.copy()

diff --git a/tests/test_linearity.py b/tests/test_linearity.py
@@ -107,7 +107,7 @@ def _create_ptc(self, amp_names, exp_times, means, ccobcurr=None, photo_charges=
                     inputExpIdPair=exp_id_pairs[i],
                     rawExpTime=exp_times[i],
                     rawMean=raw_mean,
-                    rawVar=1.0,
+                    rawVar=raw_mean,
                     kspValue=1.0,
                     expIdMask=exp_id_mask,
                     photoCharge=photo_charges[i],