DeferredChargeCalib¶

class lsst.ip.isr.DeferredChargeCalib(**kwargs)¶

Bases: IsrCalib

Calibration containing deferred charge/CTI parameters.

This includes, parameters from Snyder+2021 and exstimates of the serial and parallel CTI using the extended pixel edge response (EPER) method (also defined in Snyder+2021).

Parameters:

**kwargs: Additional parameters to pass to parent constructor.

Notes

The charge transfer inefficiency attributes stored are:

driftScaledict [str, float]: A dictionary, keyed by amplifier name, of the local electronic offset drift scale parameter, A_L in Snyder+2021.
decayTimedict [str, float]: A dictionary, keyed by amplifier name, of the local electronic offset decay time, tau_L in Snyder+2021.
globalCtidict [str, float]: A dictionary, keyed by amplifier name, of the mean global CTI paramter, b in Snyder+2021.
serialTrapsdict [str, lsst.ip.isr.SerialTrap]: A dictionary, keyed by amplifier name, containing a single serial trap for each amplifier.
signalsdict [str, np.ndarray]: A dictionary, keyed by amplifier name, of the mean signal level for each input measurement.
serialEperdict [str, np.ndarray, float]: A dictionary, keyed by amplifier name, of the serial EPER estimator of serial CTI, given in a list for each input measurement.
parallelEperdict [str, np.ndarray, float]: A dictionary, keyed by amplifier name, of the parallel EPER estimator of parallel CTI, given in a list for each input measurement.
serialCtiTurnoffdict [str, float]: A dictionary, keyed by amplifier name, of the serial CTI turnoff (unit: electrons).
parallelCtiTurnoffdict [str, float]: A dictionary, keyed by amplifier name, of the parallel CTI turnoff (unit: electrons).
serialCtiTurnoffSamplingErrdict [str, float]: A dictionary, keyed by amplifier name, of the serial CTI turnoff sampling error (unit: electrons).
parallelCtiTurnoffSamplingErrdict [str, float]: A dictionary, keyed by amplifier name, of the parallel CTI turnoff sampling error (unit: electrons).

Also, the values contained in this calibration are all derived from and image and overscan in units of electron as these are the most natural units in which to compute deferred charge. However, this means the the user should supply a reliable set of gains when computing the CTI statistics during ISR.

Version 1.1 deprecates the USEGAINS attribute and standardizes: everything to electron units.
Version 1.2 adds the signal, serialEper, parallelEper,: serialCtiTurnoff, parallelCtiTurnoff, serialCtiTurnoffSamplingErr, parallelCtiTurnoffSamplingErr attributes.

Attributes Summary

`metadata`
`requiredAttributes`

Methods Summary

`apply`(target)	Method to apply the calibration to the target object.
`calibInfoFromDict`(dictionary)	Handle common keywords.
`determineCalibClass`(metadata, message)	Attempt to find calibration class in metadata.
`fromDetector`(detector)	Read metadata parameters from a detector.
`fromDict`(dictionary)	Construct a calibration from a dictionary of properties.
`fromTable`(tableList)	Construct calibration from a list of tables.
`getMetadata`()	Retrieve metadata associated with this calibration.
`readFits`(filename, **kwargs)	Read calibration data from a FITS file.
`readText`(filename, **kwargs)	Read calibration representation from a yaml/ecsv file.
`setMetadata`(metadata)	Store a copy of the supplied metadata with this calibration.
`toDict`()	Return a dictionary containing the calibration properties.
`toTable`()	Construct a list of tables containing the information in this calibration.
`updateMetadata`([camera, detector, ...])	Update metadata keywords with new values.
`updateMetadataFromExposures`(exposures)	Extract and unify metadata information.
`validate`([other])	Validate that this calibration is defined and can be used.
`writeFits`(filename)	Write calibration data to a FITS file.
`writeText`(filename[, format])	Write the calibration data to a text file.

Attributes Documentation

metadata¶

requiredAttributes¶

Methods Documentation

apply(target)¶

Method to apply the calibration to the target object.

Parameters:

targetobject: Thing to validate against.

Returns:

validbool: Returns true if the calibration was applied correctly.

Raises:

NotImplementedError: Raised if not implemented.

calibInfoFromDict(dictionary)¶

Handle common keywords.

This isn’t an ideal solution, but until all calibrations expect to find everything in the metadata, they still need to search through dictionaries.

Parameters:

dictionarydict or lsst.daf.base.PropertyList: Source for the common keywords.

Raises:

RuntimeError: Raised if the dictionary does not match the expected OBSTYPE.

classmethod determineCalibClass(metadata, message)¶

Attempt to find calibration class in metadata.

Parameters:

metadatadict or lsst.daf.base.PropertyList: Metadata possibly containing a calibration class entry.
messagestr: Message to include in any errors.

Returns:

calibClassobject: The class to use to read the file contents. Should be an lsst.ip.isr.IsrCalib subclass.

Raises:

ValueError: Raised if the resulting calibClass is the base lsst.ip.isr.IsrClass (which does not implement the content methods).

fromDetector(detector)¶

Read metadata parameters from a detector.

Parameters:

detectorlsst.afw.cameraGeom.detector: Input detector with parameters to use.

Returns:

caliblsst.ip.isr.Linearizer: The calibration constructed from the detector.

classmethod fromDict(dictionary)¶

Construct a calibration from a dictionary of properties.

Parameters:

dictionarydict: Dictionary of properties.

Returns:

caliblsst.ip.isr.CalibType: Constructed calibration.

Raises:

RuntimeError: Raised if the supplied dictionary is for a different calibration.

classmethod fromTable(tableList)¶

Construct calibration from a list of tables.

This method uses the fromDict method to create the calibration, after constructing an appropriate dictionary from the input tables.

Parameters:

tableListlist [lsst.afw.table.Table]: List of tables to use to construct the CTI calibration. Two tables are expected in this list, the first containing the per-amplifier CTI parameters, and the second containing the parameters for serial traps.

Returns:

caliblsst.ip.isr.DeferredChargeCalib: The calibration defined in the tables.

Raises:

ValueError: Raised if the trap type or trap coefficients are not defined properly.

getMetadata()¶

Retrieve metadata associated with this calibration.

Returns:

metalsst.daf.base.PropertyList: Metadata. The returned PropertyList can be modified by the caller and the changes will be written to external files.

classmethod readFits(filename, **kwargs)¶

Read calibration data from a FITS file.

Parameters:

filenamestr: Filename to read data from.
kwargsdict or collections.abc.Mapping`, optional: Set of key=value pairs to pass to the fromTable method.

Returns:

caliblsst.ip.isr.IsrCalib: Calibration contained within the file.

classmethod readText(filename, **kwargs)¶

Read calibration representation from a yaml/ecsv file.

Parameters:

filenamestr: Name of the file containing the calibration definition.
kwargsdict or collections.abc.Mapping`, optional: Set of key=value pairs to pass to the fromDict or fromTable methods.

Returns:

calibIsrCalibType: Calibration class.

Raises:

RuntimeError: Raised if the filename does not end in “.ecsv” or “.yaml”.

setMetadata(metadata)¶

Store a copy of the supplied metadata with this calibration.

Parameters:

metadatalsst.daf.base.PropertyList: Metadata to associate with the calibration. Will be copied and overwrite existing metadata.

toDict()¶

Return a dictionary containing the calibration properties. The dictionary should be able to be round-tripped through fromDict.

Returns:

dictionarydict: Dictionary of properties.

toTable()¶

Construct a list of tables containing the information in this calibration.

The list of tables should create an identical calibration after being passed to this class’s fromTable method.

Returns:

tableListlist [lsst.afw.table.Table]: List of tables containing the crosstalk calibration information. Two tables are generated for this list, the first containing the per-amplifier CTI parameters, and the second containing the parameters for serial traps.

updateMetadata(camera=None, detector=None, filterName=None, setCalibId=False, setCalibInfo=False, setDate=False, **kwargs)¶

Update metadata keywords with new values.

Parameters:

cameralsst.afw.cameraGeom.Camera, optional: Reference camera to use to set _instrument field.
detectorlsst.afw.cameraGeom.Detector, optional: Reference detector to use to set _detector* fields.
filterNamestr, optional: Filter name to assign to this calibration.
setCalibIdbool, optional: Construct the _calibId field from other fields.
setCalibInfobool, optional: Set calibration parameters from metadata.
setDatebool, optional: Ensure the metadata CALIBDATE fields are set to the current datetime.
kwargsdict or collections.abc.Mapping, optional: Set of key=value pairs to assign to the metadata.

updateMetadataFromExposures(exposures)¶

Extract and unify metadata information.

Parameters:

exposureslist: Exposures or other calibrations to scan.

validate(other=None)¶

Validate that this calibration is defined and can be used.

Parameters:

otherobject, optional: Thing to validate against.

Returns:

validbool: Returns true if the calibration is valid and appropriate.

writeFits(filename)¶

Write calibration data to a FITS file.

Parameters:

filenamestr: Filename to write data to.

Returns:

usedstr: The name of the file used to write the data.

writeText(filename, format='auto')¶

Write the calibration data to a text file.

Parameters:

filenamestr

Name of the file to write.

formatstr

Format to write the file as. Supported values are:: "auto" : Determine filetype from filename. "yaml" : Write as yaml. "ecsv" : Write as ecsv.

Returns:

usedstr: The name of the file used to write the data. This may differ from the input if the format is explicitly chosen.

Raises:

RuntimeError: Raised if filename does not end in a known extension, or if all information cannot be written.

Notes

The file is written to YAML/ECSV format and will include any associated metadata.

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DeferredChargeCalib¶