FitSipDistortionTask

class lsst.meas.astrom.FitSipDistortionTask(**kwargs)

Bases: Task

Fit a TAN-SIP WCS given a list of reference object/source matches.

Methods Summary

display(revFitter[, exposure, bbox, frame, ...])	Display positions and outlier status overlaid on an image.
emptyMetadata()	Empty (clear) the metadata for this Task and all sub-Tasks.
fitWcs(matches, initWcs[, bbox, refCat, ...])	Fit a TAN-SIP WCS from a list of reference object/source matches.
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.
makeInitialWcs(matches, wcs)	Generate a guess Wcs from the astrometric matches
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

display(revFitter, exposure=None, bbox=None, frame=0, pause=True)

Display positions and outlier status overlaid on an image.

This method is called by fitWcs when display debugging is enabled. It always drops into pdb before returning to allow interactive inspection, and hence it should never be called in non-interactive contexts.

Parameters:

revFitterlsst::meas::astrom::ScaledPolynomialTransformFitter

Fitter object initialized with fromMatches for fitting a “reverse” distortion: the mapping from intermediate world coordinates to pixels.

exposurelsst::afw::image::Exposure

An Exposure or other displayable image on which matches can be overplotted.

bboxlsst::afw::geom::Box2I

Bounding box of the region on which matches should be plotted.

emptyMetadata() → None

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

fitWcs(matches, initWcs, bbox=None, refCat=None, sourceCat=None, exposure=None)

Fit a TAN-SIP WCS from a list of reference object/source matches.

Parameters:

matcheslist of lsst.afw.table.ReferenceMatch

A sequence of reference object/source matches. The following fields are read: - match.first (reference object) coord - match.second (source) centroid

The following fields are written: - match.first (reference object) centroid - match.second (source) centroid - match.distance (on sky separation, in radians)

initWcslsst.afw.geom.SkyWcs

An initial WCS whose CD matrix is used as the final CD matrix.

bboxlsst.geom.Box2I

The region over which the WCS will be valid (PARENT pixel coordinates); if None or an empty box then computed from matches

refCatlsst.afw.table.SimpleCatalog

Reference object catalog, or None. If provided then all centroids are updated with the new WCS, otherwise only the centroids for ref objects in matches are updated. Required fields are “centroid_x”, “centroid_y”, “coord_ra”, and “coord_dec”.

sourceCatlsst.afw.table.SourceCatalog

Source catalog, or None. If provided then coords are updated with the new WCS; otherwise only the coords for sources in matches are updated. Required input fields are “slot_Centroid_x”, “slot_Centroid_y”, “slot_Centroid_xErr”, “slot_Centroid_yErr”, and optionally “slot_Centroid_x_y_Cov”. The “coord_ra” and “coord_dec” fields will be updated but are not used as input.

exposurelsst.afw.image.Exposure

An Exposure or other displayable image on which matches can be overplotted. Ignored (and may be None) if display-based debugging is not enabled via lsstDebug.

Returns:

An lsst.pipe.base.Struct with the following fields:

• wcslsst.afw.geom.SkyWcs

  The best-fit WCS.

• scatterOnSkylsst.geom.Angle

  The median on-sky separation between reference objects and sources in “matches”, as an lsst.geom.Angle

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

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")

makeInitialWcs(matches, wcs)

Generate a guess Wcs from the astrometric matches

We create a Wcs anchored at the center of the matches, with the scale of the input Wcs. This is necessary because the Wcs may have a very approximation position (as is common with telescoped-generated Wcs). We’re using the best of each: positions from the matches, and scale from the input Wcs.

Parameters:

matcheslist of lsst::afw::table::ReferenceMatch

A sequence of reference object/source matches. The following fields are read:

• match.first (reference object) coord

• match.second (source) centroid

wcslsst::afw::geom::SkyWcs

An initial WCS whose CD matrix is used as the CD matrix of the result.

Returns:

newWcslsst.afw.geom.SkyWcs

A new WCS guess.

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.

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.

logLevel

A logging level constant.

See also

lsst.utils.timer.logInfo

Examples

Creating a timer context:

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