CircleSkyRegion

class regions.CircleSkyRegion(center, radius, meta=None, visual=None)

Bases: SkyRegion

A circle defined using sky coordinates.

Parameters:

centerSkyCoord

The center position.

radiusQuantity

The radius 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.
meta	The meta attributes as a RegionMeta
radius	The 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 PolygonSkyRegion that approximates this circle.
to_spherical_sky(*[, wcs, ...])	Convert to an equivalent spherical SphericalSkyRegion instance.

Attributes Documentation

center

The center position as a astropy.coordinates.SkyCoord.

meta

The meta attributes as a RegionMeta

radius

The radius as a astropy.units.Quantity angle.

visual

The visual attributes as a RegionVisual.

Methods Documentation

to_pixel(wcs, *, as_ellipse=False)

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 EllipsePixelRegion instead of a CirclePixelRegion. An ellipse is generally a better approximation when the WCS has distortions or different pixel scales along different axes. Default is False.

Returns:

regionCirclePixelRegion or EllipsePixelRegion

The pixel region. An ellipse is returned if as_ellipse is True.

to_polygon(wcs, *, n_vertices=100)

Return a PolygonSkyRegion that approximates this circle.

Parameters:

wcsWCS

The WCS to use for the sky-to-pixel-to-sky conversion.

n_verticesint, optional

The number of polygon vertices. Default is 100.

Returns:

polygonPolygonSkyRegion

A polygon region approximating the circle.

to_spherical_sky(*, wcs=None, boundary_distortions=False, n_vertices=None)

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).