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

classPhotonTransferCurveSolveTask(*, config=None, log=None, initInputs=None, **kwargs): Task to fit the PTC from flat covariances...

attributeconfig: Access configuration fields and retargetable subtasks.

methodrun(inputCovariances, camera=None, inputExpList=None): Fit measured covariances to different models...

Retargetable subtasks¶

No subtasks.

Configuration fields¶

connections¶

Data type: lsst.pipe.base.config.Connections
Field type: ConfigField

Configurations describing the connections of the PipelineTask to datatypes

consecutivePointsVarDecreases¶

Default: 2
Field type: int RangeField
Range: [2,inf)

Required number of consecutive points/fluxes in the PTC where the variance decreases in order to find a first estimate of the PTC turn-off.

doFitBootstrap¶

Default: False
Field type: bool Field

Use bootstrap for the PTC fit parameters and errors?.

maxIterFullFitCovariancesAstier¶

Default: 3
Field type: int Field

Maximum number of iterations in full model fit for FULLCOVARIANCE ptcFitType

maxIterationsPtcOutliers¶

Default: 2
Field type: int RangeField
Range: [0,inf)

Maximum number of iterations for outlier rejection in PTC.

maximumRangeCovariancesAstier¶

Default: 8
Field type: int Field

Maximum range of covariances as in Astier+19

minVarPivotSearch¶

Default: 10000
Field type: float Field

The code looks for a pivot signal point after which the variance starts decreasing at high-flux to exclude then from 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¶

Default: 3
Field type: int Field

Degree of polynomial to fit the PTC, when ‘ptcFitType’=POLYNOMIAL.

ptcFitType¶

Default

'POLYNOMIAL'

Field type

str ChoiceField (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)
None: Field is optional

Fit PTC to Eq. 16, Eq. 20 in Astier+19, or to a polynomial.

saveLogOutput¶

Default: True
Field type: bool Field

Flag to enable/disable saving of log output for a task, enabled by default.

saveMetadata¶

Default: True
Field type: bool Field

Flag to enable/disable metadata saving for a task, enabled by default.

sigmaClipFullFitCovariancesAstier¶

Default: 5.0
Field type: float Field

sigma clip for full model fit for FULLCOVARIANCE ptcFitType

sigmaCutPtcOutliers¶

Default: 5.0
Field type: float Field

Sigma cut for outlier rejection in PTC.

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