lsst.meas.base.forcedPhotCoadd.ForcedPhotCoaddTask Class Reference

A command-line driver for performing forced measurement on coadd images. More...

Inheritance diagram for lsst.meas.base.forcedPhotCoadd.ForcedPhotCoaddTask:

Public Member Functions
def	getExposure
def	makeIdFactory
def	fetchReferences
def	attachFootprints

Static Public Attributes
	ConfigClass = ForcedPhotCoaddConfig
	RunnerClass = lsst.pipe.base.ButlerInitializedTaskRunner
string	dataPrefix = "deepCoadd_"

Private Member Functions
def	_makeArgumentParser

Static Private Attributes
string	_DefaultName = "forcedPhotCoadd"

Detailed Description

A command-line driver for performing forced measurement on coadd images.

This task is a subclass of ForcedPhotImageTask which is specifically for doing forced measurement on a coadd, using as a reference catalog detections which were made on overlapping coadds (i.e. in other bands).

The run method (inherited from ForcedPhotImageTask) takes a lsst.daf.persistence.ButlerDataRef argument that corresponds to a coadd image. This is used to provide all the inputs and outputs for the task:

• A "*Coadd_src" (e.g. "deepCoadd_src") dataset is used as the reference catalog. This not loaded directly from the passed dataRef, however; only the patch and tract are used, while the filter is set by the configuration for the references subtask (see CoaddSrcReferencesTask).
• A "*Coadd_calexp" (e.g. "deepCoadd_calexp") dataset is used as the measurement image. Note that this means that ProcessCoaddTask must be run on an image before ForcedPhotCoaddTask, in order to generate the "*Coadd_calexp" dataset.
• A "*Coadd_forced_src" (e.g. "deepCoadd_forced_src") dataset will be written with the output measurement catalog.

In addition to the run method, ForcedPhotCcdTask overrides several methods of ForcedPhotImageTask to specialize it for coadd processing, including makeIdFactory() and fetchReferences(). None of these should be called directly by the user, though it may be useful to override them further in subclasses.

Definition at line 60 of file forcedPhotCoadd.py.

Member Function Documentation

def lsst.meas.base.forcedPhotCoadd.ForcedPhotCoaddTask._makeArgumentParser (   cls )

private

Definition at line 151 of file forcedPhotCoadd.py.

    def _makeArgumentParser(cls):
        parser = lsst.pipe.base.ArgumentParser(name=cls._DefaultName)
        parser.add_id_argument("--id", "deepCoadd_forced_src", help="data ID, with raw CCD keys + tract",
                               ContainerClass=lsst.coadd.utils.CoaddDataIdContainer)
        return parser

def lsst.meas.base.forcedPhotCoadd.ForcedPhotCoaddTask.attachFootprints	(		self,
			sources,
			refCat,
			exposure,
			refWcs,
			dataRef
	)

For coadd forced photometry, we use the deblended HeavyFootprints from the single-band
measurements of the same band - because we've guaranteed that the peaks (and hence child sources)
will be consistent across all bands before we get to measurement, this should yield reasonable
deblending for most sources.  It's most likely limitation is that it will not provide good flux
upper limits for sources that were not detected in this band but were blended with sources that
were.

Definition at line 127 of file forcedPhotCoadd.py.

    def attachFootprints(self, sources, refCat, exposure, refWcs, dataRef):
        """For coadd forced photometry, we use the deblended HeavyFootprints from the single-band
        measurements of the same band - because we've guaranteed that the peaks (and hence child sources)
        will be consistent across all bands before we get to measurement, this should yield reasonable
        deblending for most sources.  It's most likely limitation is that it will not provide good flux
        upper limits for sources that were not detected in this band but were blended with sources that
        were.
        """
        if self.config.footprintDatasetName is None:
            return ForcedPhotImageTask.attachFootprints(sources, refCat, exposure, refWcs, dataRef)
        self.log.info("Loading deblended footprints for sources from %s, %s" %
                      (self.config.footprintDatasetName, dataRef.dataId))
        fpCat = dataRef.get("%sCoadd_%s" % (self.config.coaddName, self.config.footprintDatasetName),
                            immediate=True)
        for refRecord, srcRecord in zip(refCat, sources):
            fpRecord = fpCat.find(refRecord.getId())
            if fpRecord is None:
                raise LookupError("Cannot find Footprint for source %s; please check that %sCoadd_%s"
                                  "IDs are compatible with reference source IDs" %
                                  (srcRecord.getId(), self.config.coaddName,
                                   self.config.footprintDatasetName))
            srcRecord.setFootprint(fpRecord.getFootprint())