DetectCoaddSourcesTask¶

class lsst.pipe.tasks.multiBand.DetectCoaddSourcesTask(schema=None, **kwargs)¶

Bases: PipelineTask

Detect sources on a single filter coadd.

Coadding individual visits requires each exposure to be warped. This introduces covariance in the noise properties across pixels. Before detection, we correct the coadd variance by scaling the variance plane in the coadd to match the observed variance. This is an approximate approach – strictly, we should propagate the full covariance matrix – but it is simple and works well in practice.

After scaling the variance plane, we detect sources and generate footprints by delegating to the @ref SourceDetectionTask_ “detection” subtask.

DetectCoaddSourcesTask is meant to be run after assembling a coadded image in a given band. The purpose of the task is to update the background, detect all sources in a single band and generate a set of parent footprints. Subsequent tasks in the multi-band processing procedure will merge sources across bands and, eventually, perform forced photometry.

Parameters:

schemalsst.afw.table.Schema, optional: Initial schema for the output catalog, modified-in place to include all fields set by this task. If None, the source minimal schema will be used.
**kwargs: Additional keyword arguments.

Attributes Summary

canMultiprocess

Methods Summary

`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.
`getName`()	Get the name of the task.
`getTaskDict`()	Get a dictionary of all tasks as a shallow copy.
`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.
`run`(exposure, idFactory, expId)	Run detection on an exposure.
`runQuantum`(butlerQC, inputRefs, outputRefs)	Do butler IO and transform to provide in memory objects for tasks `run` method.
`timer`(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.

Attributes Documentation

canMultiprocess: ClassVar[bool] = True¶

Methods Documentation

emptyMetadata() → None¶: Empty (clear) the metadata for this Task and all sub-Tasks.

getFullMetadata() → TaskMetadata¶

Get metadata for all tasks.

Returns:

metadataTaskMetadata: 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:

fullNamestr

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”.

getName() → str¶

Get the name of the task.

Returns:

taskNamestr: Name of the task.

See also

getFullName: Get the full name of the task.

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

Get a dictionary of all tasks as a shallow copy.

Returns:

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

classmethod makeField(doc: str) → ConfigurableField¶

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

Parameters:

docstr: Help text for the field.

Returns:

configurableFieldlsst.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: Any) → None¶

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

Parameters:

namestr

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.

run(exposure, idFactory, expId)¶

Run detection on an exposure.

First scale the variance plane to match the observed variance using ScaleVarianceTask. Then invoke the SourceDetectionTask_ “detection” subtask to detect sources.

Parameters:

exposurelsst.afw.image.Exposure: Exposure on which to detect (may be backround-subtracted and scaled, depending on configuration).
idFactorylsst.afw.table.IdFactory: IdFactory to set source identifiers.
expIdint: Exposure identifier (integer) for RNG seed.

Returns:

resultlsst.pipe.base.Struct

Results as a struct with attributes:

sources: Catalog of detections (lsst.afw.table.SourceCatalog).
backgrounds: List of backgrounds (list).

runQuantum(butlerQC, inputRefs, outputRefs)¶

Do butler IO and transform to provide in memory objects for tasks run method.

Parameters:

butlerQCQuantumContext: A butler which is specialized to operate in the context of a lsst.daf.butler.Quantum.
inputRefsInputQuantizedConnection: Datastructure whose attribute names are the names that identify connections defined in corresponding PipelineTaskConnections class. The values of these attributes are the lsst.daf.butler.DatasetRef objects associated with the defined input/prerequisite connections.
outputRefsOutputQuantizedConnection: Datastructure whose attribute names are the names that identify connections defined in corresponding PipelineTaskConnections class. The values of these attributes are the lsst.daf.butler.DatasetRef objects associated with the defined output connections.

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

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

Parameters:

namestr: Name of code being timed; data will be logged using item name: Start and End.
logLevelint: A logging level constant.

Navigation

DetectCoaddSourcesTask¶