apply_smoothing_and_coord_transform

pysm3.apply_smoothing_and_coord_transform(input_map, fwhm=None, beam_window=None, rot=None, lmax=None, output_nside=None, output_car_resol=None, return_healpix=True, return_car=False, input_alm=False, map2alm_lsq_maxiter=None, map_dist=None, pre_applied_fwhm=None)

Apply smoothing and coordinate rotation to an input map

it applies the healpy.smoothing Gaussian smoothing kernel if map_dist is None, otherwise applies distributed smoothing with libsharp. In the distributed case, no rotation is supported.

If the input map carries a pre-applied beam (the pre_applied_fwhm attribute, set by the models of components whose templates are not beam-free), or one is provided with the pre_applied_fwhm argument, and a target fwhm is requested, only the differential beam sqrt(max(fwhm**2 - pre_applied_fwhm**2, 0)) is applied, so that the requested resolution is not over-smoothed by double-applying part of the beam the map already has. A fwhm not larger than the pre-applied beam results in no smoothing (a map cannot be deconvolved), with a warning. In serial execution, the returned HEALPix map is tagged with the beam it carries after smoothing, so that repeated smoothing stays differential; in the distributed case the smoothed map is not tagged.

Parameters:

input_mapndarray

Input map, of shape (3, npix) This is assumed to have no beam at this point, as the simulated small scale template on which the simulations are based have no beam, unless a pre-applied beam is declared with pre_applied_fwhm or attached to the map as attribute.

fwhmastropy.units.Quantity

Full width at half-maximum, defining the Gaussian kernels to be applied.

pre_applied_fwhmastropy.units.Quantity or string, optional

FWHM of the Gaussian beam already applied to the input map, any angular unit (e.g. "56 arcmin"). If None (default), it is detected from the pre_applied_fwhm attribute of the input map, if present. An explicit value, including 0, takes precedence over the attribute.

beam_window: array, optional

Custom beam window function (\(B_\ell\))

rot: hp.Rotator

Apply a coordinate rotation give a healpy Rotator, e.g. if the inputs are in Galactic, hp.Rotator(coord=("G", "C")) rotates to Equatorial

output_nsideint

HEALPix output map Nside, if None, use the same as the input

lmaxint

lmax for the map2alm step, if None, it is set to 2.5 * nside if output_nside is equal or higher than nside. It is set to 1.5 * nside if output_nside is lower than nside

output_car_resolastropy.Quantity

CAR output map resolution, generally in arcmin

return_healpixbool

Whether to return the HEALPix map

return_carbool

Whether to return the CAR map

input_almbool

Instead of starting from a map, input_map is a set of Alm

map2alm_lsq_maxiterint

Number of iteration for the least squares map to Alm transform, setting it to 0 uses the standard map2alm, the default of 10 makes the transform slow if the input map is not band limited, for example if has point sources or sharp features. If ell_max is <= 1.5 nside, this setting is ignored and map2alm with pixel weights is used.

map_distpysm.MapDistribution, optional

Distribution object for parallel computing with MPI. When it is not None, the smoothing is executed with libsharp on the distributed map: no rotation (other than identity), no bandpass CAR output and no change of output NSIDE are supported, and the returned map is not tagged with its beam. With no beam to apply, the input map is returned unchanged.

Returns:

smoothed_mapnp.ndarray or tuple of np.ndarray

Array containing the smoothed sky or tuple of HEALPix and CAR maps