Merge pull request #131 from lsst/tickets/DM-47303

DM-47303: Add cameraGain config option and pipeline for building lookup table.

pipelines/LSSTComCam/fgcmMakeLUT.yaml

@@ -0,0 +1,4 @@
+description: Make LSSTComCam fgcmcal look-up table
+instrument: lsst.obs.lsst.LsstComCam
+imports:
+  - location: $FGCMCAL_DIR/pipelines/_ingredients/fgcmMakeLUT.yaml

pipelines/_ingredients/fgcmMakeLUT.yaml

@@ -0,0 +1,3 @@
+description: Make fgcmcal look-up table
+tasks:
+  fgcmMakeLut: lsst.fgcmcal.fgcmMakeLut.FgcmMakeLutTask

python/lsst/fgcmcal/fgcmFitCycle.py

@@ -688,6 +688,13 @@ class FgcmFitCycleConfig(pipeBase.PipelineTaskConfig,
         default=None,
         optional=True,
     )
+    cameraGain = pexConfig.Field(
+        doc="Average camera gain. If not set, will use the median of the "
+            "camera model/detector/amplifier gains.",
+        dtype=float,
+        default=None,
+        optional=True,
+    )
     defaultCameraOrientation = pexConfig.Field(
         doc="Default camera orientation for QA plots.",
         dtype=float,

python/lsst/fgcmcal/utilities.py

@@ -109,9 +109,12 @@ def makeConfigDict(config, log, camera, maxIter,
         # Convert to square cm.
         mirrorArea = config.mirrorArea * 100.**2.
 
-    # Get approximate average camera gain:
-    gains = [amp.getGain() for detector in camera for amp in detector.getAmplifiers()]
-    cameraGain = float(np.median(gains))
+    if config.cameraGain is None:
+        # Get approximate average camera gain:
+        gains = [amp.getGain() for detector in camera for amp in detector.getAmplifiers()]
+        cameraGain = float(np.median(gains))
+    else:
+        cameraGain = config.cameraGain
 
     # Cut down the filter map to those that are in the LUT
     filterToBand = {filterName: config.physicalFilterMap[filterName] for