ProjectionRegion

class romancal.skycell.skymap.ProjectionRegion(index: int | None, skymap: SkyMap = None)[source]

Bases: object

Projection region in the loaded skymap.

Parameters:

index (int) – index of the projection region in the loaded skymap array
skymap (SkyMap) – sky map instance (defaults to global SKYMAP)

Attributes Summary

`MAX_LENGTH`
`MIN_AREA`
`data`	Projection region data.
`index`	index in the loaded skymap
`is_polar`	whether this projection region is a polar cap
`length`	diagonal length of the region
`orientation`
`pixel_scale`	degrees per pixel
`pixel_shape`	number of pixels across
`polygon`	spherical polygon representing this region
`radec_bounds`	bounds in right ascension and declination in order [xmin, ymin, xmax, ymax]
`radec_corners`	corners in right ascension and declination in clockwise order
`radec_tangent`	projection origin (tangent point with the celestial sphere) in right ascension and declination
`skycell_indices`	indices of skycells in the loaded skymap within this projection region
`skycells`	collection of all skycells in this projection region
`vectorpoint_center`	center in 3D Cartesian space on the unit sphere
`vectorpoint_corners`	corners in 3D Cartesian space on the unit sphere
`wcs`	WCS representing this skycell
`wcs_info`	WCS properties as defined in the Level 3 association schema
`xy_tangent`	projection origin (tangent point with the celestial sphere) in pixel coordinates

Methods Summary

`contains_radec`(radec)	whether the given point(s) are contained within the bounds of this projection region
`from_data`(data[, skymap])	build a projection region instance from a data array
`from_skycell_index`(index[, skymap])

Attributes Documentation

MAX_LENGTH = 0.08174916691321586

MIN_AREA = 0.002791388883915502

data

Projection region data.

(“index”, “ra_tangent”, “dec_tangent”, “ra_min”, “ra_max”, “dec_min”, “dec_max”, “orientat”, “x_tangent”, “y_tangent”, “nx”, “ny”, “skycell_start”, “skycell_end”)

index: index in the loaded skymap

is_polar: whether this projection region is a polar cap

length[source]: diagonal length of the region

orientation

pixel_scale: degrees per pixel

pixel_shape: number of pixels across

polygon[source]: spherical polygon representing this region

radec_bounds: bounds in right ascension and declination in order [xmin, ymin, xmax, ymax]

radec_corners: corners in right ascension and declination in clockwise order

radec_tangent: projection origin (tangent point with the celestial sphere) in right ascension and declination

skycell_indices[source]: indices of skycells in the loaded skymap within this projection region

skycells[source]: collection of all skycells in this projection region

vectorpoint_center[source]: center in 3D Cartesian space on the unit sphere

vectorpoint_corners[source]: corners in 3D Cartesian space on the unit sphere

wcs[source]: WCS representing this skycell

wcs_info: WCS properties as defined in the Level 3 association schema

xy_tangent: projection origin (tangent point with the celestial sphere) in pixel coordinates

Methods Documentation

contains_radec(radec: ndarray[tuple[Any, ...], dtype[float]]) → ndarray[tuple[Any, ...], dtype[bool]][source]: whether the given point(s) are contained within the bounds of this projection region

classmethod from_data(data: void, skymap: SkyMap = None) → ProjectionRegion[source]

build a projection region instance from a data array

Parameters:

data (numpy.void) – array with projection region parameters (see schema)
skymap (SkyMap) – sky map instance; defaults to global SKYMAP (Default value = None)

classmethod from_skycell_index(index: int, skymap: SkyMap = None) → ProjectionRegion[source]

Parameters:

index (int) – index of the skycell
skymap (SkyMap) – sky map instance; defaults to global SKYMAP (Default value = None)

Returns:

projection region corresponding to the given skycell

Return type:

ProjectionRegion