EvaluateLocalWcsPlugin

class lsst.meas.base.EvaluateLocalWcsPlugin(config, name, schema, metadata)

Bases: GenericPlugin

Evaluate the local, linear approximation of the Wcs.

The aim is to store the local calib value within the catalog for later use in the Science Data Model functors.

Methods Summary

getExecutionOrder()	Get the relative execution order of this plugin.
makeLocalTransformMatrix(wcs, center)	Create a local, linear approximation of the wcs transformation matrix.
measure(measRecord, exposure, center)	Measure a single source.

Methods Documentation

classmethod getExecutionOrder()

Get the relative execution order of this plugin.

Must be reimplemented as a class method by concrete derived classes.

makeLocalTransformMatrix(wcs, center)

Create a local, linear approximation of the wcs transformation matrix.

The approximation is created as if the center is at RA=0, DEC=0. All comparing x,y coordinate are relative to the position of center. Matrix is initially calculated with units arcseconds and then converted to radians. This yields higher precision results due to quirks in AST.

Parameters

wcslsst.afw.geom.SkyWcs

Wcs to approximate

centerlsst.geom.Point2D

Point at which to evaluate the LocalWcs.

Returns

localMatrixnumpy.ndarray

Matrix representation the local wcs approximation with units radians.

measure(measRecord, exposure, center)

Measure a single source.

It is the responsibility of this method to perform the desired measurement and record the result in the measRecord.

Parameters

measRecordlsst.afw.table.SourceRecord

Catalog record for the source being measured.

exposurelsst.afw.image.Exposure

Exposure on which the source is being measured.

centerlsst.geom.Point2D

Pixel coordinates of the object.

Raises

MeasurementError

Raised if the measurement fails for a known/justifiable reason.