cdshealpix.nested.lonlat_to_xy

cdshealpix.nested.lonlat_to_xy(lon, lat, num_threads=0)

Project sky coordinates to the HEALPix space.

Parameters:

lonastropy.coordinates.Longitude

The longitudes of the sky coordinates.

latastropy.coordinates.Latitude

The latitudes of the sky coordinates.

num_threadsint, optional

Specifies the number of threads to use for the computation. Default to 0 means it will choose the number of threads based on the RAYON_NUM_THREADS environment variable (if set), or the number of logical CPUs (otherwise)

Returns:

x, y: (numpy.ndarray, numpy.ndarray)

The position of the (lon, lat) coordinates in the HEALPix space. \(x \in [0, 8[\) and \(y \in [-2, 2]\)

Examples

>>> from cdshealpix import lonlat_to_xy
>>> from astropy.coordinates import Longitude, Latitude
>>> import astropy.units as u
>>> import numpy as np
>>> lon = Longitude([10, 25], u.deg)
>>> lat = Latitude([5, 10], u.deg)
>>> x, y = lonlat_to_xy(lon, lat)