SkyMap

class romancal.skycell.skymap.SkyMap(path: None | Path | str = None)[source]

Bases: object

Abstract representation of the skymap [skymap], comprising of 4058 overlapping rectangular “projection regions” defining gnomonic projection on to uniform pixel grids. The pixel scale for all projection regions is identical.

Each projection region is subdivided into ~2000 square subregions (“skycells”, ~8 million in total), each 4.6’ across. These skycells also overlap each other by a standard number of pixels.

References

[skymap]

Skymap Tessellation

Parameters:: path (None | Path | str, optional) – load skymap from the specified ASDF file (defaults to latest skycells ref on CRDS)

Attributes Summary

`model`	data model of skymap
`path`	location of skymap reference file on filesystem
`pixel_scale`	degrees per pixel
`pixel_shape`	number of pixels per skycell
`projection_regions_kdtree`	k-d tree of all projection regions in this skymap, using normalized center vectorpoints in 3D space
`skycells`	collection of all skycells in this skymap

Methods Summary

projection_regions_containing(radec)

point(s) contained by each projection region in this sky map

Attributes Documentation

model: data model of skymap

path: location of skymap reference file on filesystem

pixel_scale: degrees per pixel

pixel_shape: number of pixels per skycell

projection_regions_kdtree[source]: k-d tree of all projection regions in this skymap, using normalized center vectorpoints in 3D space

skycells[source]: collection of all skycells in this skymap

Methods Documentation

projection_regions_containing(radec: ndarray[tuple[Any, ...], dtype[float]]) → dict[int, list[int]][source]

point(s) contained by each projection region in this sky map

Parameters:: radec (NDArray[float]) – right ascension and declination of coordinate(s)
Return type:: mapping of projection region indices to indices of given points contained by that projection region