HealpixSkyMap

class lsst.skymap.healpixSkyMap.HealpixSkyMap(config, version=0)

Bases: lsst.skymap.cachingSkyMap.CachingSkyMap

HEALPix-based sky map pixelization.

We put a Tract at the position of each HEALPixel.

Parameters:

config : lsst.skymap.BaseSkyMapConfig

The configuration for this SkyMap.

version : int or tuple of int (optional)

Software version of this class, to retain compatibility with old instances.

Attributes Summary

numAngles

Methods Summary

findClosestTractPatchList(coordList)	Find closest tract and patches that overlap coordinates.
findTract(coord)	Find the tract whose inner region includes the coord.
findTractPatchList(coordList)	Find tracts and patches that overlap a region.
generateTract(index)	Generate TractInfo for the specified tract index.
getSha1()	Return a SHA1 hash that uniquely identifies this SkyMap instance.
register(name, registry)	Add SkyMap, Tract, and Patch Dimension entries to the given Gen3 Butler Registry.
updateSha1(sha1)	Add subclass-specific state or configuration options to the SHA1.

Attributes Documentation

numAngles = 4

Methods Documentation

findClosestTractPatchList(coordList)

Find closest tract and patches that overlap coordinates.

Parameters:

coordList : lsst.geom.SpherePoint

List of ICRS sky coordinates to search for.

Returns:

retList : list

list of (TractInfo, list of PatchInfo) for tracts and patches that contain, or may contain, the specified region. The list will be empty if there is no overlap.

findTract(coord)

Find the tract whose inner region includes the coord.

Parameters:

coord : lsst.geom.SpherePoint

ICRS sky coordinate to search for.

Returns:

tractInfo : TractInfo

Info for tract whose inner region includes the coord.

findTractPatchList(coordList)

Find tracts and patches that overlap a region.

Parameters:

coordList : list of lsst.geom.SpherePoint

List of ICRS sky coordinates to search for.

Returns:

reList : list of (TractInfo, list of PatchInfo)

For tracts and patches that contain, or may contain, the specified region. The list will be empty if there is no overlap.

Notes

warning:

This uses a naive algorithm that may find some tracts and patches that do not overlap the region (especially if the region is not a rectangle aligned along patch x, y).

generateTract(index)

Generate TractInfo for the specified tract index.

getSha1()

Return a SHA1 hash that uniquely identifies this SkyMap instance.

Returns:

sha1 : bytes

A 20-byte hash that uniquely identifies this SkyMap instance.

Notes

Subclasses should almost always override updateSha1 instead of this function to add subclass-specific state to the hash.

register(name, registry)

Add SkyMap, Tract, and Patch Dimension entries to the given Gen3 Butler Registry.

Parameters:

name : str

The name of the skymap.

registry : lsst.daf.butler.Registry

The registry to add to.

updateSha1(sha1)

Add subclass-specific state or configuration options to the SHA1.