AstrometryTask¶
- class lsst.meas.astrom.AstrometryTask(refObjLoader=None, schema=None, **kwargs)¶
Bases:
RefMatchTask
Match an input source catalog with objects from a reference catalog and solve for the WCS.
This task is broken into two main subasks: matching and WCS fitting which are very interactive. The matching here can be considered in part a first pass WCS fitter due to the fitter’s sensitivity to outliers.
- Parameters:
- refObjLoader
lsst.meas.algorithms.ReferenceLoader
A reference object loader object; gen3 pipeline tasks will pass
None
and callsetRefObjLoader
inrunQuantum
.- schema
lsst.afw.table.Schema
Used to set “calib_astrometry_used” flag in output source catalog.
- **kwargs
Additional keyword arguments for pipe_base
lsst.pipe.base.Task.__init__
.
- refObjLoader
Methods Summary
check
(exposure, sourceCat, nMatches)Validate the astrometric fit against the maxMeanDistance threshold.
Empty (clear) the metadata for this Task and all sub-Tasks.
Get metadata for all tasks.
Get the task name as a hierarchical name including parent task names.
getName
()Get the name of the task.
Get a dictionary of all tasks as a shallow copy.
loadAndMatch
(exposure, sourceCat)Load reference objects overlapping an exposure and match to sources detected on that exposure.
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
(sourceCat, exposure)Load reference objects, match sources and optionally fit a WCS.
setRefObjLoader
(refObjLoader)Sets the reference object loader for the task.
solve
(exposure, sourceCat)Load reference objects overlapping an exposure, match to sources and fit a WCS
timer
(name[, logLevel])Context manager to log performance data for an arbitrary block of code.
Methods Documentation
- check(exposure, sourceCat, nMatches)¶
Validate the astrometric fit against the maxMeanDistance threshold.
If the distMean metric does not satisfy the requirement of being less than the value set in config.maxMeanDistanceArcsec, the WCS on the exposure will be set to None and the coordinate values in the source catalog will be set to NaN to reflect a failed astrometric fit.
- Parameters:
- exposure
lsst.afw.image.Exposure
The exposure whose astrometric fit is being evaluated.
- sourceCat
lsst.afw.table.SourceCatalog
The catalog of sources associated with the exposure.
- nMatches
int
The number of matches that were found and used during the astrometric fit (for logging purposes only).
- exposure
- Raises:
- BadAstrometryFit
If the measured mean on-sky distance between the matched source and reference objects is greater than
self.config.maxMeanDistanceArcsec
.
- getFullMetadata() 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.
- metadata
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”.
- fullName
- getName() str ¶
Get the name of the task.
- Returns:
- taskName
str
Name of the task.
- taskName
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:
- taskDict
dict
Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.
- taskDict
- loadAndMatch(exposure, sourceCat)¶
Load reference objects overlapping an exposure and match to sources detected on that exposure.
- Parameters:
- exposure
lsst.afw.image.Exposure
exposure that the sources overlap
- sourceCat
lsst.afw.table.SourceCatalog.
catalog of sources detected on the exposure
- exposure
- Returns:
- result
lsst.pipe.base.Struct
Result struct with Components:
refCat
: reference object catalog of objects that overlap the exposure (lsst.afw.table.SimpleCatalog
)matches
: Matched sources and references (list
oflsst.afw.table.ReferenceMatch
)matchMeta
: metadata needed to unpersist matches (lsst.daf.base.PropertyList
)
- result
Notes
ignores config.matchDistanceSigma
- classmethod makeField(doc: str) ConfigurableField ¶
Make a
lsst.pex.config.ConfigurableField
for this task.- Parameters:
- doc
str
Help text for the field.
- doc
- Returns:
- configurableField
lsst.pex.config.ConfigurableField
A
ConfigurableField
for this task.
- configurableField
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:
- 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
.
- name
Notes
The subtask must be defined by
Task.config.name
, an instance ofConfigurableField
orRegistryField
.
- run(sourceCat, exposure)¶
Load reference objects, match sources and optionally fit a WCS.
This is a thin layer around solve or loadAndMatch, depending on config.forceKnownWcs.
- Parameters:
- exposure
lsst.afw.image.Exposure
exposure whose WCS is to be fit The following are read only:
bbox
filter (may be unset)
detector (if wcs is pure tangent; may be absent)
The following are updated:
wcs (the initial value is used as an initial guess, and is required)
- sourceCat
lsst.afw.table.SourceCatalog
catalog of sources detected on the exposure
- exposure
- Returns:
- result
lsst.pipe.base.Struct
with these fields:
refCat
: reference object catalog of objects that overlap the exposure (with some margin) (lsst.afw.table.SimpleCatalog
).matches
: astrometric matches (list
oflsst.afw.table.ReferenceMatch
).scatterOnSky
: median on-sky separation between reference objects and sources in “matches” (lsst.afw.geom.Angle
) orNone
if config.forceKnownWcs TruematchMeta
: metadata needed to unpersist matches (lsst.daf.base.PropertyList
)
- result
- setRefObjLoader(refObjLoader)¶
Sets the reference object loader for the task.
- Parameters:
- refObjLoader
An instance of a reference object loader task or class.
- solve(exposure, sourceCat)¶
Load reference objects overlapping an exposure, match to sources and fit a WCS
- Returns:
- result
lsst.pipe.base.Struct
Result struct with components:
refCat
: reference object catalog of objects that overlap the exposure (with some margin) (lsst::afw::table::SimpleCatalog
).matches
: astrometric matches (list
oflsst.afw.table.ReferenceMatch
).scatterOnSky
: median on-sky separation between reference objects and sources in “matches” (lsst.geom.Angle
)matchMeta
: metadata needed to unpersist matches (lsst.daf.base.PropertyList
)
- result
- Raises:
- BadAstrometryFit
If the measured mean on-sky distance between the matched source and reference objects is greater than
self.config.maxMeanDistanceArcsec
.
Notes
ignores config.forceKnownWcs