SkyRegion

class regions.SkyRegion

Bases: Region

Base class for all regions defined in celestial coordinates.

Methods Summary

contains(skycoord, wcs)	Check whether a sky coordinate falls inside the region.
intersection(other)	Return a region representing the intersection of this region with other.
symmetric_difference(other)	Return the union of the two regions minus any areas contained in the intersection of the two regions.
to_pixel(wcs)	Return the equivalent region defined in pixel coordinates.
to_spherical_sky([wcs, ...])	Convert to an equivalent spherical SphericalSkyRegion instance.
union(other)	Return a region representing the union of this region with other.

Methods Documentation

contains(skycoord, wcs)

Check whether a sky coordinate falls inside the region.

Parameters:

skycoordSkyCoord

The position or positions to check.

wcsWCS

The world coordinate system transformation to use to convert between sky and pixel coordinates.

intersection(other)

Return a region representing the intersection of this region with other.

Parameters:

otherRegion

The other region to use for the intersection.

symmetric_difference(other)

Return the union of the two regions minus any areas contained in the intersection of the two regions.

Parameters:

otherRegion

The other region to use for the symmetric difference.

abstractmethod to_pixel(wcs)

Return the equivalent region defined in pixel coordinates.

Parameters:

wcsWCS

The world coordinate system transformation to use to convert between sky and pixel coordinates.

Returns:

pixel_regionPixelRegion

A pixel region.

Notes

The conversion between sky and pixel coordinates is an approximation. The sky region shape is mapped to a pixel region shape using the local pixel scale and angle at the region center. Projection effects over the extent of the region are not accounted for. The region shape type is always preserved (e.g., a CircleSkyRegion converts to a CirclePixelRegion).

For WCS with distortions (e.g., SIP), the local Jacobian matrix of the WCS transformation is used to compute directional scale factors and angle. For WCS without distortions, a local pixel scale and angle are computed using offset-based methods.

abstractmethod to_spherical_sky(wcs=None, include_boundary_distortions=False, n_points=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 include_boundary_distortions is True). Ignored if boundary distortions not included.

include_boundary_distortionsbool, optional

If True, accounts for boundary distortions in spherical to planar conversions, by discretizing the boundary and converting the boundary polygon. Default is False, which converts to an equivalent idealized shape.

n_pointsint, optional

The number of polygon vertices for boundary discretization. This keyword will have effect unless include_boundary_distortions=True. Default is 100.

Returns:

spherical_sky_regionSphericalSkyRegion

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

union(other)

Return a region representing the union of this region with other.

Parameters:

otherRegion

The other region to use for the union.