lsst.meas.algorithms.loadReferenceObjects Namespace Reference

Classes
class	_FilterCatalog
class	LoadReferenceObjectsConfig
class	LoadReferenceObjectsTask
	Abstract base class to load objects from reference catalogs. More...
class	ReferenceObjectLoader

Functions
def	isOldFluxField (name, units)
def	hasNanojanskyFluxUnits (schema)
def	getFormatVersionFromRefCat (refCat)
def	convertToNanojansky (catalog, log, doConvert=True)
def	getRefFluxField (schema, filterName=None)
def	getRefFluxKeys (schema, filterName=None)
def	joinMatchListWithCatalogImpl (refObjLoader, matchCat, sourceCat)
def	applyProperMotionsImpl (log, catalog, epoch)

Function Documentation

applyProperMotionsImpl()

def lsst.meas.algorithms.loadReferenceObjects.applyProperMotionsImpl	(		log,
			catalog,
			epoch
	)

Apply proper motion correction to a reference catalog.

Adjust position and position error in the ``catalog``
for proper motion to the specified ``epoch``,
modifying the catalong in place.

Parameters
----------
log : `lsst.log.log`
    log object to write to
catalog : `lsst.afw.table.SimpleCatalog`
    Catalog of positions, containing:

    - Coordinates, retrieved by the table's coordinate key.
    - ``coord_raErr`` : Error in Right Ascension (rad).
    - ``coord_decErr`` : Error in Declination (rad).
    - ``pm_ra`` : Proper motion in Right Ascension (rad/yr,
        East positive)
    - ``pm_raErr`` : Error in ``pm_ra`` (rad/yr), optional.
    - ``pm_dec`` : Proper motion in Declination (rad/yr,
        North positive)
    - ``pm_decErr`` : Error in ``pm_dec`` (rad/yr), optional.
    - ``epoch`` : Mean epoch of object (an astropy.time.Time)
epoch : `astropy.time.Time` (optional)
    Epoch to which to correct proper motion and parallax,
    or None to not apply such corrections.

Definition at line 1456 of file loadReferenceObjects.py.

def applyProperMotionsImpl(log, catalog, epoch):
    """Apply proper motion correction to a reference catalog.

    Adjust position and position error in the ``catalog``
    for proper motion to the specified ``epoch``,
    modifying the catalong in place.

    Parameters
    ----------
    log : `lsst.log.log`
        log object to write to
    catalog : `lsst.afw.table.SimpleCatalog`
        Catalog of positions, containing:

        - Coordinates, retrieved by the table's coordinate key.
        - ``coord_raErr`` : Error in Right Ascension (rad).
        - ``coord_decErr`` : Error in Declination (rad).
        - ``pm_ra`` : Proper motion in Right Ascension (rad/yr,
            East positive)
        - ``pm_raErr`` : Error in ``pm_ra`` (rad/yr), optional.
        - ``pm_dec`` : Proper motion in Declination (rad/yr,
            North positive)
        - ``pm_decErr`` : Error in ``pm_dec`` (rad/yr), optional.
        - ``epoch`` : Mean epoch of object (an astropy.time.Time)
    epoch : `astropy.time.Time` (optional)
        Epoch to which to correct proper motion and parallax,
        or None to not apply such corrections.
    """
    if "epoch" not in catalog.schema or "pm_ra" not in catalog.schema or "pm_dec" not in catalog.schema:
        log.warn("Proper motion correction not available from catalog")
        return
    if not catalog.isContiguous():
        raise RuntimeError("Catalog must be contiguous")
    catEpoch = astropy.time.Time(catalog["epoch"], scale="tai", format="mjd")
    log.debug("Correcting reference catalog for proper motion to %r", epoch)
    # Use `epoch.tai` to make sure the time difference is in TAI
    timeDiffsYears = (epoch.tai - catEpoch).to(astropy.units.yr).value
    coordKey = catalog.table.getCoordKey()
    # Compute the offset of each object due to proper motion
    # as components of the arc of a great circle along RA and Dec
    pmRaRad = catalog["pm_ra"]
    pmDecRad = catalog["pm_dec"]
    offsetsRaRad = pmRaRad*timeDiffsYears
    offsetsDecRad = pmDecRad*timeDiffsYears
    # Compute the corresponding bearing and arc length of each offset
    # due to proper motion, and apply the offset
    # The factor of 1e6 for computing bearing is intended as
    # a reasonable scale for typical values of proper motion
    # in order to avoid large errors for small values of proper motion;
    # using the offsets is another option, but it can give
    # needlessly large errors for short duration
    offsetBearingsRad = numpy.arctan2(pmDecRad*1e6, pmRaRad*1e6)
    offsetAmountsRad = numpy.hypot(offsetsRaRad, offsetsDecRad)
    for record, bearingRad, amountRad in zip(catalog, offsetBearingsRad, offsetAmountsRad):
        record.set(coordKey,
                   record.get(coordKey).offset(bearing=bearingRad*lsst.geom.radians,
                                               amount=amountRad*lsst.geom.radians))
    # Increase error in RA and Dec based on error in proper motion
    if "coord_raErr" in catalog.schema:
        catalog["coord_raErr"] = numpy.hypot(catalog["coord_raErr"],
                                             catalog["pm_raErr"]*timeDiffsYears)
    if "coord_decErr" in catalog.schema:
        catalog["coord_decErr"] = numpy.hypot(catalog["coord_decErr"],
                                              catalog["pm_decErr"]*timeDiffsYears)

convertToNanojansky()

def lsst.meas.algorithms.loadReferenceObjects.convertToNanojansky	(		catalog,
			log,
			doConvert = True
	)

Convert fluxes in a catalog from jansky to nanojansky.

Parameters
----------
catalog : `lsst.afw.table.SimpleCatalog`
    The catalog to convert.
log : `lsst.log.Log`
    Log to send messages to.
doConvert : `bool`, optional
    Return a converted catalog, or just identify the fields that need to be converted?
    This supports the "write=False" mode of `bin/convert_to_nJy.py`.

Returns
-------
catalog : `lsst.afw.table.SimpleCatalog` or None
    The converted catalog, or None if ``doConvert`` is False.

Notes
-----
Support for old units in reference catalogs will be removed after the
release of late calendar year 2019.
Use `meas_algorithms/bin/convert_to_nJy.py` to update your reference catalog.

Definition at line 89 of file loadReferenceObjects.py.

def convertToNanojansky(catalog, log, doConvert=True):
    """Convert fluxes in a catalog from jansky to nanojansky.

    Parameters
    ----------
    catalog : `lsst.afw.table.SimpleCatalog`
        The catalog to convert.
    log : `lsst.log.Log`
        Log to send messages to.
    doConvert : `bool`, optional
        Return a converted catalog, or just identify the fields that need to be converted?
        This supports the "write=False" mode of `bin/convert_to_nJy.py`.

    Returns
    -------
    catalog : `lsst.afw.table.SimpleCatalog` or None
        The converted catalog, or None if ``doConvert`` is False.

    Notes
    -----
    Support for old units in reference catalogs will be removed after the
    release of late calendar year 2019.
    Use `meas_algorithms/bin/convert_to_nJy.py` to update your reference catalog.
    """
    # Do not share the AliasMap: for refcats, that gets created when the
    # catalog is read from disk and should not be propagated.
    mapper = lsst.afw.table.SchemaMapper(catalog.schema, shareAliasMap=False)
    mapper.addMinimalSchema(lsst.afw.table.SimpleTable.makeMinimalSchema())
    input_fields = []
    output_fields = []
    for field in catalog.schema:
        oldName = field.field.getName()
        oldUnits = field.field.getUnits()
        if isOldFluxField(oldName, oldUnits):
            units = 'nJy'
            # remap Sigma flux fields to Err, so we can drop the alias
            if oldName.endswith('_fluxSigma'):
                name = oldName.replace('_fluxSigma', '_fluxErr')
            else:
                name = oldName
            newField = lsst.afw.table.Field[field.dtype](name, field.field.getDoc(), units)
            mapper.addMapping(field.getKey(), newField)
            input_fields.append(field.field)
            output_fields.append(newField)
        else:
            mapper.addMapping(field.getKey())

    fluxFieldsStr = '; '.join("(%s, '%s')" % (field.getName(), field.getUnits()) for field in input_fields)

    if doConvert:
        newSchema = mapper.getOutputSchema()
        output = lsst.afw.table.SimpleCatalog(newSchema)
        output.extend(catalog, mapper=mapper)
        for field in output_fields:
            output[field.getName()] *= 1e9
        log.info(f"Converted refcat flux fields to nJy (name, units): {fluxFieldsStr}")
        return output
    else:
        log.info(f"Found old-style refcat flux fields (name, units): {fluxFieldsStr}")
        return None

getFormatVersionFromRefCat()

def lsst.meas.algorithms.loadReferenceObjects.getFormatVersionFromRefCat

(

refCat

)

"Return the format version stored in a reference catalog header.

Parameters
----------
refCat : `lsst.afw.table.SimpleCatalog`
    Reference catalog to inspect.

Returns
-------
version : `int` or `None`
    Format version integer, or `None` if the catalog has no metadata
    or the metadata does not include a "REFCAT_FORMAT_VERSION" key.

Definition at line 66 of file loadReferenceObjects.py.

def getFormatVersionFromRefCat(refCat):
    """"Return the format version stored in a reference catalog header.

    Parameters
    ----------
    refCat : `lsst.afw.table.SimpleCatalog`
        Reference catalog to inspect.

    Returns
    -------
    version : `int` or `None`
        Format version integer, or `None` if the catalog has no metadata
        or the metadata does not include a "REFCAT_FORMAT_VERSION" key.
    """
    md = refCat.getMetadata()
    if md is None:
        return None
    try:
        return md.getScalar("REFCAT_FORMAT_VERSION")
    except KeyError:
        return None

getRefFluxField()

def lsst.meas.algorithms.loadReferenceObjects.getRefFluxField	(		schema,
			filterName = None
	)

Get the name of a flux field from a schema.

if filterName is specified:
    return *filterName*_camFlux if present
    else return *filterName*_flux if present (camera filter name matches reference filter name)
    else throw RuntimeError
else:
    return camFlux, if present,
    else throw RuntimeError

Parameters
----------
schema : `lsst.afw.table.Schema`
    Reference catalog schema.
filterName : `str`
    Name of camera filter.

Returns
-------
fluxFieldName : `str`
    Name of flux field.

Raises
------
RuntimeError
    If an appropriate field is not found.

Definition at line 687 of file loadReferenceObjects.py.

def getRefFluxField(schema, filterName=None):
    """Get the name of a flux field from a schema.

    if filterName is specified:
        return *filterName*_camFlux if present
        else return *filterName*_flux if present (camera filter name matches reference filter name)
        else throw RuntimeError
    else:
        return camFlux, if present,
        else throw RuntimeError

    Parameters
    ----------
    schema : `lsst.afw.table.Schema`
        Reference catalog schema.
    filterName : `str`
        Name of camera filter.

    Returns
    -------
    fluxFieldName : `str`
        Name of flux field.

    Raises
    ------
    RuntimeError
        If an appropriate field is not found.
    """
    if not isinstance(schema, afwTable.Schema):
        raise RuntimeError("schema=%s is not a schema" % (schema,))
    if filterName:
        fluxFieldList = [filterName + "_camFlux", filterName + "_flux"]
    else:
        fluxFieldList = ["camFlux"]
    for fluxField in fluxFieldList:
        if fluxField in schema:
            return fluxField

    raise RuntimeError("Could not find flux field(s) %s" % (", ".join(fluxFieldList)))

getRefFluxKeys()

def lsst.meas.algorithms.loadReferenceObjects.getRefFluxKeys	(		schema,
			filterName = None
	)

Return keys for flux and flux error.

Parameters
----------
schema : `lsst.afw.table.Schema`
    Reference catalog schema.
filterName : `str`
    Name of camera filter.

Returns
-------
keys : `tuple` of (`lsst.afw.table.Key`, `lsst.afw.table.Key`)
    Two keys:

    - flux key
    - flux error key, if present, else None

Raises
------
RuntimeError
    If flux field not found.

Definition at line 728 of file loadReferenceObjects.py.

def getRefFluxKeys(schema, filterName=None):
    """Return keys for flux and flux error.

    Parameters
    ----------
    schema : `lsst.afw.table.Schema`
        Reference catalog schema.
    filterName : `str`
        Name of camera filter.

    Returns
    -------
    keys : `tuple` of (`lsst.afw.table.Key`, `lsst.afw.table.Key`)
        Two keys:

        - flux key
        - flux error key, if present, else None

    Raises
    ------
    RuntimeError
        If flux field not found.
    """
    fluxField = getRefFluxField(schema, filterName)
    fluxErrField = fluxField + "Err"
    fluxKey = schema[fluxField].asKey()
    try:
        fluxErrKey = schema[fluxErrField].asKey()
    except Exception:
        fluxErrKey = None
    return (fluxKey, fluxErrKey)

hasNanojanskyFluxUnits()

def lsst.meas.algorithms.loadReferenceObjects.hasNanojanskyFluxUnits

(

schema

)

Return True if the units of all flux and fluxErr are correct (nJy).

Definition at line 57 of file loadReferenceObjects.py.

def hasNanojanskyFluxUnits(schema):
    """Return True if the units of all flux and fluxErr are correct (nJy).
    """
    for field in schema:
        if isOldFluxField(field.field.getName(), field.field.getUnits()):
            return False
    return True

isOldFluxField()

def lsst.meas.algorithms.loadReferenceObjects.isOldFluxField	(		name,
			units
	)

Return True if this name/units combination corresponds to an
"old-style" reference catalog flux field.

Definition at line 46 of file loadReferenceObjects.py.

def isOldFluxField(name, units):
    """Return True if this name/units combination corresponds to an
    "old-style" reference catalog flux field.
    """
    unitsCheck = units != 'nJy'  # (units == 'Jy' or units == '' or units == '?')
    isFlux = name.endswith('_flux')
    isFluxSigma = name.endswith('_fluxSigma')
    isFluxErr = name.endswith('_fluxErr')
    return (isFlux or isFluxSigma or isFluxErr) and unitsCheck

joinMatchListWithCatalogImpl()

def lsst.meas.algorithms.loadReferenceObjects.joinMatchListWithCatalogImpl	(		refObjLoader,
			matchCat,
			sourceCat
	)

Relink an unpersisted match list to sources and reference
objects.

A match list is persisted and unpersisted as a catalog of IDs
produced by afw.table.packMatches(), with match metadata
(as returned by the astrometry tasks) in the catalog's metadata
attribute. This method converts such a match catalog into a match
list, with links to source records and reference object records.

Parameters
----------
refObjLoader
    Reference object loader to use in getting reference objects
matchCat : `lsst.afw.table.BaseCatalog`
    Unperisted packed match list.
    ``matchCat.table.getMetadata()`` must contain match metadata,
    as returned by the astrometry tasks.
sourceCat : `lsst.afw.table.SourceCatalog`
    Source catalog. As a side effect, the catalog will be sorted
    by ID.

Returns
-------
matchList : `lsst.afw.table.ReferenceMatchVector`
    Match list.

Definition at line 1395 of file loadReferenceObjects.py.

def joinMatchListWithCatalogImpl(refObjLoader, matchCat, sourceCat):
    """Relink an unpersisted match list to sources and reference
    objects.

    A match list is persisted and unpersisted as a catalog of IDs
    produced by afw.table.packMatches(), with match metadata
    (as returned by the astrometry tasks) in the catalog's metadata
    attribute. This method converts such a match catalog into a match
    list, with links to source records and reference object records.

    Parameters
    ----------
    refObjLoader
        Reference object loader to use in getting reference objects
    matchCat : `lsst.afw.table.BaseCatalog`
        Unperisted packed match list.
        ``matchCat.table.getMetadata()`` must contain match metadata,
        as returned by the astrometry tasks.
    sourceCat : `lsst.afw.table.SourceCatalog`
        Source catalog. As a side effect, the catalog will be sorted
        by ID.

    Returns
    -------
    matchList : `lsst.afw.table.ReferenceMatchVector`
        Match list.
    """
    matchmeta = matchCat.table.getMetadata()
    version = matchmeta.getInt('SMATCHV')
    if version != 1:
        raise ValueError('SourceMatchVector version number is %i, not 1.' % version)
    filterName = matchmeta.getString('FILTER').strip()
    try:
        epoch = matchmeta.getDouble('EPOCH')
    except (pexExcept.NotFoundError, pexExcept.TypeError):
        epoch = None  # Not present, or not correct type means it's not set
    if 'RADIUS' in matchmeta:
        # This is a circle style metadata, call loadSkyCircle
        ctrCoord = lsst.geom.SpherePoint(matchmeta.getDouble('RA'),
                                         matchmeta.getDouble('DEC'), lsst.geom.degrees)
        rad = matchmeta.getDouble('RADIUS') * lsst.geom.degrees
        refCat = refObjLoader.loadSkyCircle(ctrCoord, rad, filterName, epoch=epoch).refCat
    elif "INNER_UPPER_LEFT_RA" in matchmeta:
        # This is the sky box type (only triggers in the LoadReferenceObject class, not task)
        # Only the outer box is required to be loaded to get the maximum region, all filtering
        # will be done by the unpackMatches function, and no spatial filtering needs to be done
        # by the refObjLoader
        box = []
        for place in ("UPPER_LEFT", "UPPER_RIGHT", "LOWER_LEFT", "LOWER_RIGHT"):
            coord = lsst.geom.SpherePoint(matchmeta.getDouble(f"OUTER_{place}_RA"),
                                          matchmeta.getDouble(f"OUTER_{place}_DEC"),
                                          lsst.geom.degrees).getVector()
            box.append(coord)
        outerBox = sphgeom.ConvexPolygon(box)
        refCat = refObjLoader.loadRegion(outerBox, filterName=filterName, epoch=epoch).refCat

    refCat.sort()
    sourceCat.sort()
    return afwTable.unpackMatches(matchCat, refCat, sourceCat)

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