LegacyPointSpreadFunction

class lsst.images.psfs.LegacyPointSpreadFunction(impl: Any, bounds: Bounds)

Bases: PointSpreadFunction

A PSF model backed by a legacy lsst.afw.detection.Psf object.

Parameters

impl

An lsst.afw.detection.Psf instance.

bounds

The pixel-coordinate region where the model can safely be evaluated.

Notes

This wrapper is usable as-is on any lsst.afw.detection.Psf instance, but subclasses (e.g. PSFExWrapper) must be used for serialization.

Attributes Summary

bounds	The region where this PSF model is valid.
kernel_bbox	Bounding box of all images returned by compute_kernel_image.
legacy_psf	The backing lsst.afw.detection.Psf object.

Methods Summary

compute_kernel_image(*, x, y)	Evaluate the PSF model into an image suitable for convolution.
compute_stellar_bbox(*, x, y)	Return the bounding box of the image that would be returned by compute_stellar_image.
compute_stellar_image(*, x, y)	Evaluate the PSF model into an image suitable for comparison with the image of an astrophysical point source.
from_legacy(legacy_psf, bounds)	Make a PSF object from a legacy lsst.afw.detection.Psf instance.

Attributes Documentation

bounds

kernel_bbox

legacy_psf

The backing lsst.afw.detection.Psf object.

Methods Documentation

compute_kernel_image(*, x: float, y: float) → Image

Evaluate the PSF model into an image suitable for convolution.

Parameters

x

Column position coordinate to evaluate at.

y

Row position coordinate to evaluate at.

Returns

Image

An image of the PSF, centered on the center of the center pixel, which is defined to be (0, 0) by the image’s origin.

compute_stellar_bbox(*, x: float, y: float) → Box

Return the bounding box of the image that would be returned by compute_stellar_image.

Parameters

x

Column position coordinate to evaluate at.

y

Row position coordinate to evaluate at.

Returns

Box

The bounding box of the image that would be returned by compute_stellar_image at the given point.

compute_stellar_image(*, x: float, y: float) → Image

Evaluate the PSF model into an image suitable for comparison with the image of an astrophysical point source.

Parameters

x

Column position coordinate to evaluate at.

y

Row position coordinate to evaluate at.

Returns

Image

An image of the PSF, centered on the given coordinates, just like the postage stamp of a star would be.

classmethod from_legacy(legacy_psf: Any, bounds: Bounds) → LegacyPointSpreadFunction

Make a PSF object from a legacy lsst.afw.detection.Psf instance.

Parameters

legacy_psf

Legacy PSF object.

bounds

The region where this PSF model is valid.

Returns

PointSpreadFunction

A PointSpreadFunction instance.

Notes

This base class method is a factory dispatch function that automatically selects the right PointSpreadFunction subclass to use. When that is already known, a subclass from_legacy method can be called instead.