ialteralm
This IDL facility provides an interface to F90 'alteralm' facility.
This program can be used to modify a set of alm spherical harmonics
coefficients, as those extracted by ianafast or
simulated by isynfast, before
they are used as constraints on a isynfast run. Currently the alterations
possible are
rotation (using Wigner matrices) of the alm from the input
coordinate system to any other standard astrophysical coordinate system. The
resulting alm can be used with e.g. synfast to generate a map in the
new coordinate system.
removal of the pixel and beam window functions of the input
alm (corresponding to the pixel size and beam shape of the map from which
they were extracted) and implementation of an arbitrary pixel and beam window
function.
 |
(6) |
where P(l) is the pixel window function, and B(l) is the beam window
function (assuming a circular beam) or any other l space filter (eg,
Wiener filter). For an infinitely small pixel (or beam) one would have P(l) =
1 (resp. B(l) = 1) for any l.
Location in HEALPix directory tree: src/idl/interfaces/ialteralm.pro
FORMAT
QUALIFIERS
-
alm_in
- required input: input alm, must be a FITS file
-
alm_out
- required output: output alm, must be a FITS file
KEYWORDS
-
binpath=
- full path to back-end routine default:$HEXE/alteralm, then $HEALPIX/bin/alteralm
- a binpath starting with / (or
), or $ is interpreted as absolute
- a binpath starting with ./ is interpreted as relative to current directory
- all other binpathes are relative to $HEALPIX
-
beam_file_in=
- Beam window function of input alm,
either a FITS file or an array. If present, will override
fwhm_arcmin_in
default:value of BEAM_LEG keyword read from
alm_in
-
beam_file_out=
- Beam window function of output alm,
either a FITS file or an array. If present and non-empty, will override
fwhm_arcmin_out
default:'' (empty string, no beam window applied)
-
coord_in=
- Astrophysical coordinates system used to compute input alm.
Case-insensitive single letter code.
Valid choices are 'g','G' = Galactic, 'e','E' = Ecliptic,
'c','q','C','Q' = Celestial/eQuatorial.
default:value of COORDSYS keyword read from
alm_in
-
coord_out=
- Astrophysical coordinates system of output alm.
default: coord_in
-
epoch_in=
- Astronomical epoch of input coordinates
(coord_in)
default:2000.0
-
epoch_out=
- Astronomical epoch of output coordinates
(coord_out)
default:same as epoch_in
-
fwhm_arcmin_in=
- Full Width
Half-Maximum in arcmin of Gaussian beam applied to map from which are obtained
input alm.
default:value of FWHM keyword in alm_in
-
fwhm_arcmin_out=
- FWHM in
arcmin to be applied to output alm.
default:fwhm_arcmin_in
-
/help
- if set, prints extended help
-
/keep_tmp_files
- if set,
temporary files are not discarded at the end of the run
-
lmax_out=, nlmax_out=
- maximum multipole of output alm
-
nside_in=, nsmax_in=
- HEALPix resolution parameter of map
from which were computed input alm
default:determined from alm_in
-
nside_out=,nsmax_out=
- HEALPix resolution parameter Nside whose
window function will be applied to output alm.
Could be set to 0 for infinitely small pixels (no window)
default:same as input nsmax_in
-
/silent
- if set, works silently
-
tmpdir=
- directory in which are written temporary files
default:IDL_TMPDIR (see IDL documentation)
DESCRIPTION
ialteralm is an interface to 'alteralm' F90 facility. It
requires some disk space on which to write the parameter file and the other
temporary files. Most data can be provided/generated as an external FITS
file, or as a memory array.
RELATED ROUTINES
This section lists the routines related to ialteralm
-
idl
- version 6.4 or more is necessary to run ialteralm.
-
alteralm
- F90 facility called by ialteralm.
-
ianafast
- IDL Interface to F90 anafast and C++ anafast_cxx
-
iprocess_mask
- IDL Interface to F90 process_mask
-
ismoothing
- IDL Interface to F90 smoothing
-
isynfast
- IDL Interface to F90 synfast
EXAMPLE:
This example script reads the test (polarised) alm located in $HEALPIX/test/alm.fits and rotates them from Galactic to Equatorial
coordinates, it then synthetizes a map out of those,
and finally plots its I and Q Stokes components (in Equatorial coordinates)
Version 3.30, 2015-10-08