healpy.sphtfunc.gauss_beam(fwhm, lmax=512, pol=False)

Gaussian beam window function

Computes the spherical transform of an axisimmetric gaussian beam

For a sky of underlying power spectrum C(l) observed with beam of given FWHM, the measured power spectrum will be C(l)_meas = C(l) B(l)^2 where B(l) is given by gaussbeam(Fwhm,Lmax). The polarization beam is also provided (when pol = True ) assuming a perfectly co-polarized beam (e.g., Challinor et al 2000, astro-ph/0008228)


fwhm : float

full width half max in radians

lmax : integer

ell max

pol : bool

if False, output has size (lmax+1) and is temperature beam if True output has size (lmax+1, 4) with components: * temperature beam * grad/electric polarization beam * curl/magnetic polarization beam * temperature * grad beam


beam : array

beam window function [0, lmax] if dim not specified otherwise (lmax+1, 4) contains polarized beam