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write_tqu
This IDL facility writes a temperature+polarization Healpix map (T,Q,U) into a
binary table FITS file,
with optionally the error (dT,dQ,dU) and correlation (dQU, dTU, dTQ)
in separate extensions
Location in HEALPix directory tree:
src/idl/fits/write_tqu.pro
FORMAT IDL>
WRITE_TQU , File, TQU, [Coordsys=, Nested=, Ring=, Ordering=, Error=, Extension=,
Help=, Hdr=, Xhdr=, Units=, Help=]
QUALIFIERS
-
File
- name of a FITS file in which the maps are to be written
-
TQU
- : array of Healpix maps of size (,3,n_ext) where is the total
number of Healpix pixels on the sky, and n_ext 3.
Three maps are written in each extension of the FITS file :
-the temperature+polarization Stokes parameters maps (T,Q,U) in
extension 0
-the error maps (dT,dQ,dU) (if n_ext 2) in extension 1
-the correlation maps (dQU, dTU, dTQ) (if n_ext = 3) in extension 2
it is also possible to write 3 maps directly in a given
extension (provided the preceding extension, if any, is already
filled in)
by setting Extension to the extension number in which to write
(0 based) and if n_ext + Extension 3
-
Coordsys=
- (optional),
if set to either 'C', 'E' or 'G', specifies that the
Healpix coordinate system is respectively Celestial=equatorial,
Ecliptic or Galactic.
(The relevant keyword is then added/updated in the extension
header, but the map is NOT rotated)
-
Error=
- (optional output),
will take value 1 if file can not be written
-
Extension=
- (optional),
extension unit a which to put the data (0 based). The physical
interpretation of the maps is determined by the
extension in which they are written
see also:TQU
-
Hdr=
- (optional),
string variable containing on input the information to be added
to the primary header. (If already present, FITS reserved
keywords will be automatically updated).
-
Ordering=
- (optional),
if set to either 'ring' or 'nested' (case un-sensitive),
specifies that the map is respectively in RING or NESTED
ordering scheme
see also:Nested and Ring
-
Units=
- (optional),
string describing the physical units of the data set
-
Xhdr=
- (optional),
string variable containing on input the information to be added
to the extension headerx. (If already present, FITS reserved
keywords will be automatically updated). It will be
repeated in each extension, except for TTYPE* and EXTNAME which
are generated by the routine and depend on the extension
KEYWORDS
-
Help
- if set, an extensive help is displayed and no
file is written
-
Nested
- if set, specifies that the map is in the NESTED ordering
scheme
see also:Ordering and Ring
-
Ring
- if set, specifies that the map is in the RING ordering
scheme
see also:Ordering and Nested
DESCRIPTION
write_tqu writes out Stokes parameters (T,Q,U) maps for the whole
sky into a FITS file. It is also possible to write the error per pixel for each
map and the correlation between fields, as subsequent extensions of the same FITS
file (see qualifiers above). Therefore the file may have up to three extensions with three
maps in each. Extensions can be written together or one by one (in
their physical order) using the Extension option
RELATED ROUTINESThis section lists the routines related to write_tqu
-
idl
- version 6.1 or more is necessary to run write_tqu
-
read_tqu
- This HEALPix IDL facility can be used to read in maps
written by write_tqu.
-
read_fits_s
- This HEALPix IDL facility can be used to read
into an IDL structure maps written by write_tqu.
-
sxaddpar
- This IDL routine (included in HEALPix package) can be used to update
or add FITS keywords to the header(s) HDR or XHDR
-
write_fits_cut4,
write_fits_map
-
write_tqu,
write_fits_sb
- HEALPix IDL routines to write cut-sky maps, full-sky maps, polarized full-sky maps and
arbitrary data sets into FITS files
EXAMPLE:
The array TQU is defined to contain a fictitious polarisation map, with
the 3 Stokes parameters T, Q and U. The map is assumed to be in
Galactic coordinates, with a RING ordering of the pixels.
write_tqu writes out the contents of TQU into the extension
of the FITS file 'map_polarization.fits'.
Eric Hivon
2010-06-18
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