ReferenceObjectLoader¶
- class lsst.meas.algorithms.ReferenceObjectLoader(dataIds, refCats, name=None, log=None, config=None)¶
Bases:
object
This class facilitates loading reference catalogs.
The QuantumGraph generation will create a list of datasets that may possibly overlap a given region. These datasets are then used to construct an instance of this class. The class instance should then be passed into a task which needs reference catalogs. These tasks should then determine the exact region of the sky reference catalogs will be loaded for, and call a corresponding method to load the reference objects.
- Parameters:
- dataIdsiterable of
lsst.daf.butler.DataCoordinate
An iterable object of data IDs that point to reference catalogs.
- refCatsiterable of
lsst.daf.butler.DeferredDatasetHandle
Handles to load refCats on demand.
- name
str
, optional The name of the refcat that this object will load. This name is used for applying colorterms, for example.
- config
LoadReferenceObjectsConfig
Configuration of this reference loader.
- log
lsst.log.Log
,logging.Logger
orNone
, optional Logger object used to write out messages. If
None
a default logger will be used.
- dataIdsiterable of
Methods Summary
applyProperMotions
(catalog, epoch)Apply proper motion correction to a reference catalog.
getMetadataBox
(bbox, wcs, filterName[, ...])Return metadata about the loaded reference catalog, in an on-detector box.
getMetadataCircle
(coord, radius, filterName)Return metadata about the loaded reference catalog, in an on-sky circle.
loadPixelBox
(bbox, wcs, filterName[, epoch, ...])Load reference objects that are within a pixel-based rectangular region.
loadRegion
(region, filterName[, filtFunc, epoch])Load reference objects within a specified region.
loadSkyCircle
(ctrCoord, radius, filterName)Load reference objects that lie within a circular region on the sky.
Methods Documentation
- applyProperMotions(catalog, epoch)¶
Apply proper motion correction to a reference catalog.
Adjust position and position error in the
catalog
for proper motion to the specifiedepoch
, modifying the catalog in place.- Parameters:
- catalog
lsst.afw.table.SimpleCatalog
Catalog of positions, containing at least these fields:
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 inpm_ra
(rad/yr), optional.pm_dec
Proper motion in Declination (rad/yr,North positive)
pm_decErr
: Error inpm_dec
(rad/yr), optional.epoch
: Mean epoch of object (an astropy.time.Time)
- epoch
astropy.time.Time
Epoch to which to correct proper motion. If None, do not apply PM corrections or raise if
config.requireProperMotion
is True.
- catalog
- Raises:
- RuntimeError
Raised if
config.requireProperMotion
is set but we cannot apply the proper motion correction for some reason.
- getMetadataBox(bbox, wcs, filterName, epoch=None, bboxToSpherePadding=100)¶
Return metadata about the loaded reference catalog, in an on-detector box.
This metadata is used for reloading the catalog (e.g., for reconstituting a normalised match list).
- Parameters:
- bbox
lsst.geom.Box2I
orlsst.geom.Box2D
Bounding box for the pixels.
- wcs
lsst.afw.geom.SkyWcs
The WCS object associated with
bbox
.- filterName
str
Name of the camera filter.
- epoch
astropy.time.Time
orNone
, optional Epoch that proper motion and parallax were corrected to, or
None
if no such corrections were applied.- bboxToSpherePadding
int
, optional Padding in pixels to account for translating a set of corners into a spherical (convex) boundary that is certain to encompass the enitre area covered by the box.
- bbox
- Returns:
- md
lsst.daf.base.PropertyList
The metadata detailing the search parameters used for this dataset.
- md
- static getMetadataCircle(coord, radius, filterName, epoch=None)¶
Return metadata about the loaded reference catalog, in an on-sky circle.
This metadata is used for reloading the catalog (e.g. for reconstituting a normalized match list).
- Parameters:
- coord
lsst.geom.SpherePoint
ICRS center of the search region.
- radius
lsst.geom.Angle
Radius of the search region.
- filterName
str
Name of the camera filter.
- epoch
astropy.time.Time
orNone
, optional Epoch that proper motion and parallax were corrected to, or
None
if no such corrections were applied.
- coord
- Returns:
- md
lsst.daf.base.PropertyList
Metadata about the catalog.
- md
- loadPixelBox(bbox, wcs, filterName, epoch=None, bboxToSpherePadding=100)¶
Load reference objects that are within a pixel-based rectangular region.
This algorithm works by creating a spherical box whose corners correspond to the WCS converted corners of the input bounding box (possibly padded). It then defines a filtering function which looks at the pixel position of the reference objects and accepts only those that lie within the specified bounding box.
The spherical box region and filtering function are passed to the generic loadRegion method which loads and filters the reference objects from the datastore and returns a single catalog containing the filtered set of reference objects.
- Parameters:
- bbox
lsst.geom.Box2I
orlsst.geom.Box2D
Box which bounds a region in pixel space.
- wcs
lsst.afw.geom.SkyWcs
Wcs object defining the pixel to sky (and inverse) transform for the supplied
bbox
.- filterName
str
Name of camera filter.
- epoch
astropy.time.Time
orNone
, optional Epoch to which to correct proper motion and parallax, or
None
to not apply such corrections.- bboxToSpherePadding
int
, optional Padding to account for translating a set of corners into a spherical (convex) boundary that is certain to encompase the enitre area covered by the box.
- bbox
- Returns:
- output
lsst.pipe.base.Struct
Results struct with attributes:
refCat
Catalog containing reference objects inside the specified bounding box (padded by self.config.pixelMargin).
fluxField
Name of the field containing the flux associated with
filterName
.
- output
- Raises:
- RuntimeError
Raised if no reference catalogs could be found for the specified region.
- TypeError
Raised if the loaded reference catalogs do not have matching schemas.
- loadRegion(region, filterName, filtFunc=None, epoch=None)¶
Load reference objects within a specified region.
This function loads the DataIds used to construct an instance of this class which intersect or are contained within the specified region. The reference catalogs which intersect but are not fully contained within the input region are further filtered by the specified filter function. This function returns a single source catalog containing all reference objects inside the specified region.
- Parameters:
- region
lsst.sphgeom.Region
This can be any type that is derived from
lsst.sphgeom.Region
and should define the spatial region for which reference objects are to be loaded.- filtFunccallable or
None
, optional This optional parameter should be a callable object that takes a reference catalog and its corresponding region as parameters, filters the catalog by some criteria and returns the filtered reference catalog. If
None
, an internal filter function is used which filters according to if a reference object falls within the input region.- filterName
str
Name of camera filter.
- epoch
astropy.time.Time
orNone
, optional Epoch to which to correct proper motion and parallax, or
None
to not apply such corrections.
- region
- Returns:
- output
lsst.pipe.base.Struct
Results struct with attributes:
refCat
Catalog containing reference objects which intersect the input region, filtered by the specified filter function.
fluxField
Name of the field containing the flux associated with
filterName
.
- output
- Raises:
- RuntimeError
Raised if no reference catalogs could be found for the specified region.
- TypeError
Raised if the loaded reference catalogs do not have matching schemas.
- loadSkyCircle(ctrCoord, radius, filterName, epoch=None)¶
Load reference objects that lie within a circular region on the sky.
This method constructs a circular region from an input center and angular radius, loads reference catalogs which are contained in or intersect the circle, and filters reference catalogs which intersect down to objects which lie within the defined circle.
- Parameters:
- ctrCoord
lsst.geom.SpherePoint
Point defining the center of the circular region.
- radius
lsst.geom.Angle
Defines the angular radius of the circular region.
- filterName
str
Name of camera filter.
- epoch
astropy.time.Time
orNone
, optional Epoch to which to correct proper motion and parallax, or
None
to not apply such corrections.
- ctrCoord
- Returns:
- output
lsst.pipe.base.Struct
Results struct with attributes:
refCat
Catalog containing reference objects inside the specified search circle.
fluxField
Name of the field containing the flux associated with
filterName
.
- output