FlatGradient

class lsst.ip.isr.FlatGradient(**kwargs)

Bases: IsrCalib

Flat gradient measurements.

Parameters:

loglogging.Logger, optional

Log to write messages to. If None a default logger will be used.

**kwargs

Additional parameters.

Attributes Summary

metadata
requiredAttributes

Methods Summary

apply(target)	Method to apply the calibration to the target object.
calibInfoFromDict(dictionary)	Handle common keywords.
computeFullModel(x, y, is_itl)	Compute the full gradient model given x/y and itl booleans.
computeGradientModel(x, y)	Compute the gradient model values.
computeRadialSplineModel(radius)	Compute the radial spline model values from radii.
computeRadialSplineModelXY(x, y)	Compute the radial spline model values from x/y.
determineCalibClass(metadata, message)	Attempt to find calibration class in metadata.
fromDetector(detector)	Modify the calibration parameters to match the supplied detector.
fromDict(dictionary)	Construct a FlatGradient from a dictionary of properties.
fromTable(tableList)	Construct a 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.
setParameters(*, radialSplineNodes, ...[, ...])	Set the parameters for the gradient model.
toDict()	Return a dictionary containing the calibration properties.
toTable()	Construct a list of table(s) containing the FlatGradient data.
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.

computeFullModel(x, y, is_itl)

Compute the full gradient model given x/y and itl booleans.

This returns the full model that can be applied directly to data that was used in a fit.

Parameters:

xnp.ndarray

Array of focal plane x values (mm).

ynp.ndarray

Array of focal plane y values (mm).

is_itlnp.ndarray

Boolean array of whether each point is from an ITL detector.

Returns:

modelnp.ndarray

Model values at each position.

computeGradientModel(x, y)

Compute the gradient model values.

The gradient model is a plane constrained to be 1.0 at the centroidX, centroidY values. Dividing by this model will remove the planar gradient in a flat field. Note that the planar gradient pivot is always at the same position, and does not move with the radial gradient centroid so as to keep the model fit more stable.

Parameters:

xnp.ndarray

Array of focal plane x values (mm).

ynp.ndarray

Array of focal plane y values (mm).

Returns:

gradientModelnp.ndarray

Gradient model values at the x/y positions.

computeRadialSplineModel(radius)

Compute the radial spline model values from radii.

The spline model is a 1D Akima spline. When computed, the values from the model describe the radial function of the full focal plane flat-field. Dividing by this model will yield a radially flattened flat-field.

Parameters:

radiusnp.ndarray

Array of focal plane radii (mm).

Returns:

splineModelnp.ndarray

Spline model values at the radius positions.

computeRadialSplineModelXY(x, y)

Compute the radial spline model values from x/y.

The spline model is a 1D Akima spline. When computed, the values from the model describe the radial function of the full focal plane flat-field. Dividing by this model will yield a radially flattened flat-field.

Parameters:

xnp.ndarray

Array of focal plane x values (mm).

ynp.ndarray

Array of focal plane y values (mm).

Returns:

splineModelnp.ndarray

Spline model values at the x/y positions.

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)

Modify the calibration parameters to match the supplied detector.

Parameters:

detectorlsst.afw.cameraGeom.Detector

Detector to use to set parameters from.

Raises:

NotImplementedError

Raised if not implemented by a subclass. This needs to be implemented by subclasses for each calibration type.

classmethod fromDict(dictionary)

Construct a FlatGradient from a dictionary of properties.

Parameters:

dictionarydict

Dictionary of properties.

Returns:

caliblsst.ip.isr.FlatGradient

Constructed calibration.

classmethod fromTable(tableList)

Construct a calibration from a list of tables.

Parameters:

tableListlist [astropy.table.Table]

List of table(s) to use to construct the FlatGradient.

Returns:

caliblsst.ip.isr.FlatGradient

The calibration defined in the table(s).

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.

setParameters(*, radialSplineNodes, radialSplineValues, itlRatio=1.0, centroidX=0.0, centroidY=0.0, centroidDeltaX=0.0, centroidDeltaY=0.0, gradientX=0.0, gradientY=0.0, normalizationFactor=1.0)

Set the parameters for the gradient model.

Parameters:

radialSplineNodesnp.ndarray

Array of spline nodes.

radialSplineValuesnp.ndarray

Array of spline values (same length as radialSplineNodes).

itlRatiofloat, optional

Ratio of flat for ITL detectors to E2V detectors.

centroidXfloat, optional

X centroid of the focal plane (mm). This will be used as the pivot for the gradient plane.

centroidYfloat, optional

Y centroid of the focal plane (mm). This will be used as the pivot for the gradient plane.

centroidDeltaXfloat, optional

Centroid offset (mm). This is used in the radial function to allow for mis-centering in the illumination gradient.

centroidDeltaYfloat, optional

Centroid offset (mm). This is used in the radial function to allow for mis-centering in the illumination gradient.

gradientXfloat, optional

Slope of gradient in x direction (throughput/mm).

gradientYfloat, optional

Slope of gradient in y direction (throughput/mm).

normalizationFactorfloat, optional

Overall normalization factor (used to, e.g. make the center of the focal plane equal to 1.0 vs. a focal-plane average.

toDict()

Return a dictionary containing the calibration properties.

Returns:

dictionarydict

Dictionary of properties.

toTable()

Construct a list of table(s) containing the FlatGradient data.

Returns:

tableListlist [astropy.table.Table]

List of tables containing the FlatGradient information.

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.