TextSkyRegion

class regions.TextSkyRegion(center, text, meta=None, visual=None)

Bases: PointSkyRegion

A text string in sky coordinates.

Parameters:

centerSkyCoord

The leftmost position of the text string before rotation.

textstr

The text string.

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 leftmost position (before rotation) as a astropy.coordinates.SkyCoord.
meta	The meta attributes as a RegionMeta
visual	The visual attributes as a RegionVisual.

Methods Summary

to_pixel(wcs)	Return the equivalent region defined in pixel coordinates.
to_spherical_sky(*[, wcs, ...])	Convert to an equivalent spherical SphericalSkyRegion instance.

Attributes Documentation

center

The leftmost position (before rotation) as a astropy.coordinates.SkyCoord.

meta

The meta attributes as a RegionMeta

visual

The visual attributes as a RegionVisual.

Methods Documentation

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.

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).