lsst.meas.algorithms.loadReferenceObjects.LoadReferenceObjectsTask Class Reference

Abstract base class to load objects from reference catalogs. More...

Inheritance diagram for lsst.meas.algorithms.loadReferenceObjects.LoadReferenceObjectsTask:

Public Member Functions
def	loadPixelBox
	Load reference objects that overlap a pixel-based rectangular region. More...
def	loadSkyCircle
	Load reference objects that overlap a circular sky region. More...

Static Public Member Functions
def	makeMinimalSchema
	Make the standard schema for reference object catalogs. More...

Static Public Attributes
	ConfigClass = LoadReferenceObjectsConfig

Private Member Functions
def	_addFluxAliases

Static Private Member Functions
def	_trimToBBox
	Remove objects outside a given pixel-based bbox and set centroid and hasCentroid fields. More...

Static Private Attributes
	__metaclass__ = abc.ABCMeta
string	_DefaultName = "LoadReferenceObjects"

Detailed Description

Abstract base class to load objects from reference catalogs.

Contents

• Description
• Task initialisation
• Invoking the Task
• Schema of the reference object catalog
• Configuration parameters

Description

Abstract base class for tasks that load objects from a reference catalog in a particular region of the sky.

Implementations must subclass this class, override the loadSkyCircle method, and will typically override the value of ConfigClass with a task-specific config class.

Task initialisation

Invoking the Task

Schema of the reference object catalog

Reference object catalogs are instances of lsst.afw.table.SimpleCatalog with the following schema (other fields may also be present):

• coord: position of star on sky (an lsst.afw.coord.IcrsCoord)
• centroid: position of star on an exposure, if relevant (an lsst.afw.Point2D)
• hasCentroid: is centroid usable?
• referenceFilterName_flux: brightness in the specified reference catalog filter (Jy) Note: the function lsst.afw.image.abMagFromFlux will convert flux in Jy to AB Magnitude.
• referenceFilterName_fluxSigma (optional): brightness standard deviation (Jy); omitted if no data is available; possibly nan if data is available for some objects but not others
• cameraFilterName_camera_flux: brightness in specified camera filter (Jy)
• cameraFilterName_camera_fluxSigma (optional): brightness standard deviation in specified camera filter (Jy); omitted if no data is available; possibly nan if data is available for some objects but not others
• default_flux (optional): brightness to use if no camera filter is available (Jy); omitted unless defaultFilter is specified in the config
• default_fluxSigma (optional): brightness standard deviation to use if no camera filter is available (Jy); (Jy); omitted unless defaultFilter is specified in the config and the corresponding fluxSigma field exists
• photometric (optional): is the object usable for photometric calibration?
• resolved (optional): is the object spatially resolved?
• variable (optional): does the object have variable brightness?

Configuration parameters

See LoadReferenceObjectsConfig for a base set of configuration parameters. Most subclasses will add configuration variables.

Definition at line 82 of file loadReferenceObjects.py.

Member Function Documentation

def lsst.meas.algorithms.loadReferenceObjects.LoadReferenceObjectsTask._addFluxAliases (   self,   schema  )

private

Add aliases for camera filter fluxes to the schema

If self.config.defaultFilter then adds these aliases:
    camFlux:      <defaultFilter>_flux
    camFluxSigma: <defaultFilter>_fluxSigma, if the latter exists

For each camFilter: refFilter in self.config.filterMap adds these aliases:
    <camFilter>_camFlux:      <refFilter>_flux
    <camFilter>_camFluxSigma: <refFilter>_fluxSigma, if the latter exists

@throw RuntimeError if any reference flux field is missing from the schema

Definition at line 226 of file loadReferenceObjects.py.

    def _addFluxAliases(self, schema):
        """Add aliases for camera filter fluxes to the schema

        If self.config.defaultFilter then adds these aliases:
            camFlux:      <defaultFilter>_flux
            camFluxSigma: <defaultFilter>_fluxSigma, if the latter exists

        For each camFilter: refFilter in self.config.filterMap adds these aliases:
            <camFilter>_camFlux:      <refFilter>_flux
            <camFilter>_camFluxSigma: <refFilter>_fluxSigma, if the latter exists

        @throw RuntimeError if any reference flux field is missing from the schema
        """
        aliasMap = schema.getAliasMap()

        def addAliasesForOneFilter(filterName, refFilterName):
            """Add aliases for a single filter

            @param[in] filterName  camera filter name, or ""
                the name is <filterName>_camFlux or camFlux if filterName is None
            @param[in] refFilterName  reference filter name; <refFilterName>_flux must exist
            """
            camFluxName = filterName + "_camFlux" if filterName is not None else "camFlux"
            refFluxName = refFilterName + "_flux"
            if refFluxName not in schema:
                raise RuntimeError("Unknown reference filter %s" % (refFluxName,))
            aliasMap.set(camFluxName, refFluxName)
            refFluxErrName = refFluxName + "Sigma"
            if refFluxErrName in schema:
                camFluxErrName = camFluxName + "Sigma"
                aliasMap.set(camFluxErrName, refFluxErrName)

        if self.config.defaultFilter:
            addAliasesForOneFilter(None, self.config.defaultFilter)

        for filterName, refFilterName in self.config.filterMap.iteritems():
            addAliasesForOneFilter(filterName, refFilterName)