LoadReferenceObjectsTask

class lsst.meas.algorithms.LoadReferenceObjectsTask(config: Optional[Config] = None, name: Optional[str] = None, parentTask: Optional[Task] = None, log: Optional[Union[logging.Logger, lsst.utils.logging.LsstLogAdapter]] = None)

Bases: lsst.pipe.base.Task, lsst.meas.algorithms.ReferenceObjectLoader

Abstract gen2 base class to load objects from reference catalogs.

Deprecated since version v25.0: This task is used in gen2 only; it will be removed after v25. See DM-35671 for details on updating code to avoid this warning.

Methods Summary

applyProperMotions(catalog, epoch)	Apply proper motion correction to a reference catalog.
emptyMetadata()	Empty (clear) the metadata for this Task and all sub-Tasks.
getFullMetadata()	Get metadata for all tasks.
getFullName()	Get the task name as a hierarchical name including parent task names.
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.
getName()	Get the name of the task.
getTaskDict()	Get a dictionary of all tasks as a shallow copy.
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 overlap a circular sky region.
makeField(doc)	Make a lsst.pex.config.ConfigurableField for this task.
makeSubtask(name, **keyArgs)	Create a subtask as a new instance as the name attribute of this task.
timer(name, logLevel)	Context manager to log performance data for an arbitrary block of code.

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 specified epoch, 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 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

Epoch to which to correct proper motion. If None, do not apply PM corrections or raise if config.requireProperMotion is True.

Raises:

RuntimeError

Raised if config.requireProperMotion is set but we cannot apply the proper motion correction for some reason.

emptyMetadata() → None

Empty (clear) the metadata for this Task and all sub-Tasks.

getFullMetadata() → lsst.pipe.base._task_metadata.TaskMetadata

Get metadata for all tasks.

Returns:

metadata : TaskMetadata

The keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc.

Notes

The returned metadata includes timing information (if @timer.timeMethod is used) and any metadata set by the task. The name of each item consists of the full task name with . replaced by :, followed by . and the name of the item, e.g.:

topLevelTaskName:subtaskName:subsubtaskName.itemName

using : in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.

getFullName() → str

Get the task name as a hierarchical name including parent task names.

Returns:

fullName : str

The full name consists of the name of the parent task and each subtask separated by periods. For example:

• The full name of top-level task “top” is simply “top”.
• The full name of subtask “sub” of top-level task “top” is “top.sub”.
• The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.

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 or lsst.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 or None, 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.

Returns:

md : lsst.daf.base.PropertyList

The metadata detailing the search parameters used for this dataset.

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 or None, optional

Epoch that proper motion and parallax were corrected to, or None if no such corrections were applied.

Returns:

md : lsst.daf.base.PropertyList

Metadata about the catalog.

getName() → str

Get the name of the task.

Returns:

taskName : str

Name of the task.

See also

getFullName

getTaskDict() → Dict[str, weakref.ReferenceType[lsst.pipe.base.task.Task]]

Get a dictionary of all tasks as a shallow copy.

Returns:

taskDict : dict

Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.

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 or lsst.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 or None, 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.

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.

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.

filtFunc : callable 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 or None, optional

Epoch to which to correct proper motion and parallax, or None to not apply such corrections.

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.

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, centroids=False)

Load reference objects that overlap a circular sky region.

Parameters:

ctrCoord : lsst.geom.SpherePoint

ICRS center of search region.

radius : lsst.geom.Angle

Radius of search region.

filterName : str

Name of filter. This can be used for flux limit comparisons.

epoch : astropy.time.Time or None, optional

Epoch to which to correct proper motion and parallax, or None to not apply such corrections.

centroids : bool, optional

Add centroid fields to the loaded Schema. loadPixelBox expects these fields to exist.

Returns:

results : lsst.pipe.base.Struct

A Struct containing the following fields:

refCat

A catalog of reference objects with the standard schema, as documented in the main doc string for LoadReferenceObjects. The catalog is guaranteed to be contiguous. (lsst.afw.catalog.SimpleCatalog)

fluxField

Name of flux field for specified filterName. (str)

Notes

Note that subclasses are responsible for performing the proper motion correction, since this is the lowest-level interface for retrieving the catalog.

classmethod makeField(doc: str) → lsst.pex.config.configurableField.ConfigurableField

Make a lsst.pex.config.ConfigurableField for this task.

Parameters:

doc : str

Help text for the field.

Returns:

configurableField : lsst.pex.config.ConfigurableField

A ConfigurableField for this task.

Examples

Provides a convenient way to specify this task is a subtask of another task.

Here is an example of use:

class OtherTaskConfig(lsst.pex.config.Config):
    aSubtask = ATaskClass.makeField("brief description of task")

makeSubtask(name: str, **keyArgs) → None

Create a subtask as a new instance as the name attribute of this task.

Parameters:

name : str

Brief name of the subtask.

keyArgs

Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden:

• “config”.
• “parentTask”.

Notes

The subtask must be defined by Task.config.name, an instance of ConfigurableField or RegistryField.

timer(name: str, logLevel: int = 10) → Iterator[None]

Context manager to log performance data for an arbitrary block of code.

Parameters:

name : str

Name of code being timed; data will be logged using item name: Start and End.

logLevel

A logging level constant.

See also

timer.logInfo

Examples

Creating a timer context:

with self.timer("someCodeToTime"):
    pass  # code to time