SkyMap

class romancal.skycell.skymap.SkyMap(path: None | Path | str = None)

Bases: object

Abstract representation of the sky map, 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 sky map from the specified ASDF file (defaults to latest skycells ref on CRDS)

Attributes Summary

model	data model of sky map
path	location of sky map 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 skymap

Attributes Documentation

model

data model of sky map

path

location of sky map 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 Documentation

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

point(s) contained by each projection region in this skymap

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