PhotonTransferCurveSolveTask¶
PhotonTransferCurveSolveTask combines the partial photon transfer curve (PTC) datasets from pairs of flats, and produces the complete curve, fitting the gains, read noises, and measuring the covariances.
Processing summary¶
PhotonTransferCurveSolveTask runs these operations:
Collates the multiple single-pair input PTC datasets.
Fits either a full-covariance model, or one of two simpler approximations (polynomial and Astier+19 exponential approximation).
Persists the final complete dataset to disk.
Python API summary¶
from lsst.cp.pipe.ptc.cpSolvePtcTask import PhotonTransferCurveSolveTask
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class
PhotonTransferCurveSolveTask(*, config=None, log=None, initInputs=None, **kwargs) Task to fit the PTC from flat covariances
...
- attributeconfig
Access configuration fields and retargetable subtasks.
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method
run(inputCovariances, camera=None, inputExpList=None) Fit measure covariances to different models
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See also
See the PhotonTransferCurveSolveTask API reference for complete details.
Retargetable subtasks¶
No subtasks.
Configuration fields¶
connections¶
- Data type
lsst.pipe.base.config.Connections- Field type
Configurations describing the connections of the PipelineTask to datatypes
doFitBootstrap¶
Use bootstrap for the PTC fit parameters and errors?.
initialNonLinearityExclusionThresholdNegative¶
- Default
0.25- Field type
- Range
[0.0,1.0)
Initially exclude data points with a variance that are more than a factor of this from being linear in the negative direction, from the PTC fit. Note that these points will also be excluded from the non-linearity fit. This is done before the iterative outlier rejection, to allow an accurate determination of the sigmas for said iterative fit.
initialNonLinearityExclusionThresholdPositive¶
- Default
0.05- Field type
- Range
[0.0,1.0)
Initially exclude data points with a variance that are more than a factor of this from being linear in the positive direction, from the PTC fit. Note that these points will also be excluded from the non-linearity fit. This is done before the iterative outlier rejection, to allow an accurate determination of the sigmas for said iterative fit.
maxIterFullFitCovariancesAstier¶
Maximum number of iterations in full model fit for FULLCOVARIANCE ptcFitType
maxIterationsPtcOutliers¶
Maximum number of iterations for outlier rejection in PTC.
maximumRangeCovariancesAstier¶
Maximum range of covariances as in Astier+19
minMeanRatioTest¶
In the initial test to screen out bad points with a ratio test, points with low flux can get inadvertantly screened. This test only screens out points with flux above this value.
minVarPivotSearch¶
The code looks for a pivot signal point after which the variance starts decreasing at high-flux to exclude then form the PTC model fit. However, sometimes at low fluxes, the variance decreases slightly. Set this variable for the variance value, in ADU^2, after which the pivot should be sought.
polynomialFitDegree¶
Degree of polynomial to fit the PTC, when ‘ptcFitType’=POLYNOMIAL.
ptcFitType¶
- Default
'POLYNOMIAL'- Field type
strChoiceField(optional)- Choices
'POLYNOMIAL'n-degree polynomial (use ‘polynomialFitDegree’ to set ‘n’).
'EXPAPPROXIMATION'Approximation in Astier+19 (Eq. 16).
'FULLCOVARIANCE'Full covariances model in Astier+19 (Eq. 20)
NoneField is optional
Fit PTC to Eq. 16, Eq. 20 in Astier+19, or to a polynomial.
saveLogOutput¶
Flag to enable/disable saving of log output for a task, enabled by default.
saveMetadata¶
Flag to enable/disable metadata saving for a task, enabled by default.
sigmaClipFullFitCovariancesAstier¶
sigma clip for full model fit for FULLCOVARIANCE ptcFitType
sigmaCutPtcOutliers¶
Sigma cut for outlier rejection in PTC.