CircleAnnulusSkyRegion#

class regions.CircleAnnulusSkyRegion(center, inner_radius, outer_radius, meta=None, visual=None)[source]#

A circular annulus in sky coordinates.

Parameters:

centerSkyCoord: The position of the center of the annulus.
inner_radiusQuantity: The inner radius of the annulus in angular units.
outer_radiusQuantity: The outer radius of the annulus in angular units.
metaRegionMeta or dict, optional: A dictionary that stores the meta attributes of the region.
visualRegionVisual or dict, optional: A dictionary that stores the visual meta attributes of the region.

Attributes Summary

`center`	The center position as a `astropy.coordinates.SkyCoord`.
`inner_radius`	The inner radius as a `astropy.units.Quantity` angle.
`meta`	The meta attributes as a `RegionMeta`
`outer_radius`	The outer radius as a `astropy.units.Quantity` angle.
`visual`	The visual attributes as a `RegionVisual`.

Methods Summary

`to_pixel`(wcs, *[, as_ellipse])	Return a pixel region from this sky region.
`to_polygon`(wcs, *[, n_vertices])	Return a `CompoundSkyRegion` of two `PolygonSkyRegion` objects that approximates this annulus.
`to_spherical_sky`(*[, wcs, ...])	Convert to an equivalent spherical `SphericalSkyRegion` instance.

Attributes Documentation

Methods Documentation

to_pixel(wcs, *, as_ellipse=False)[source]#

Return a pixel region from this sky region.

Parameters:

wcsWCS object: A world coordinate system (WCS) transformation that supports the astropy shared interface for WCS (e.g., astropy.wcs.WCS).
as_ellipsebool, optional: If True, return an EllipseAnnulusPixelRegion instead of a CircleAnnulusPixelRegion. An ellipse annulus is generally a better approximation when the WCS has distortions or different pixel scales along different axes. Default is False.

Returns:

regionCircleAnnulusPixelRegion or EllipseAnnulusPixelRegion: The pixel region. An ellipse annulus is returned if as_ellipse is True.

to_polygon(wcs, *, n_vertices=100)[source]#

Return a CompoundSkyRegion of two PolygonSkyRegion objects that approximates this annulus.

Parameters:

wcsWCS: The WCS to use for the sky-to-pixel-to-sky conversion.
n_verticesint, optional: The number of polygon vertices for each circle. Default is 100.

Returns:

polygonCompoundSkyRegion: A compound region of two polygon regions approximating the annulus.

to_spherical_sky(*, wcs=None, boundary_distortions=False, n_vertices=None)[source]#

Convert to an equivalent spherical SphericalSkyRegion instance.

Parameters:

wcsWCS instance, optional: The world coordinate system transformation to use to convert between sky and pixel coordinates. Required if transforming with boundary distortions (if boundary_distortions is True). Ignored if boundary distortions not included.
boundary_distortionsbool, optional: If True, the projection-induced distortions of the region’s boundary are preserved by discretizing the boundary into a polygon and transforming that polygon. If False (default), the region is converted to an equivalent idealized shape that ignores these boundary distortions.
n_verticesint, optional: The number of polygon vertices for boundary discretization. This keyword will have no effect unless boundary_distortions=True. Default is 100.

Returns:

spherical_sky_regionSphericalSkyRegion: A spherical sky region, with an equivalent shape (if boundary_distortions is False), or a discretized polygon of the boundary (if boundary_distortions is True).