write_fits_cut4


This IDL facility writes out a cut sky HEALPix map into a FITS file according to the HEALPix convention. The format used for the FITS file follows the one used for Boomerang98 and is adapted from COBE/DMR


Location in HEALPix directory tree: src/idl/fits/write_fits_cut4.pro


FORMAT

IDL> WRITE_FITS_CUT4 , File, Pixel, Signal [, N_Obs, Serror, XHDR=, COORDSYS=, NESTED=, RING=, ORDERING=, NSIDE=, UNITS=]


QUALIFIERS


File
name of a FITS file in which the map is to be written

Pixel
(LONG vector),
index of observed (or valid) pixels

Signal
(FLOAT vector, same size as Pixel),
value of signal in each observed pixel

N_Obs
(LONG or INT vector, Optional, same size as Pixel),
number of observation per pixel

Serror
(FLOAT vector, Optional, same size as Pixel)
rms of signal in pixel, for white noise, this is $ \propto$ 1/$ \sqrt{{\rm n\_obs}}$

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)

NSIDE=
(optional),
scalar integer, HEALPix resolution parameter of the data set. The resolution parameter should be made available to the FITS file, either thru this qualifier, or via the header (see XHDR).

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
The ordering information should be made available to the FITS file, either thru a combination of Ordering/Ring/Nested, or via the header (see XHDR).

UNITS=
(optional),
string describing the physical units of the data set (only applies to Signal and Serror)

XHDR=
(optional),
String array containing the information to be put in the extension header.


KEYWORDS


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



RELATED ROUTINES

This section lists the routines related to write_fits_cut4


idl
version 5.0 or more is necessary to run write_fits_cut4
read_fits_map
This HEALPix IDL facility can be used to read in maps written by write_fits_cut4 .
sxaddpar
This IDL routine (included in HEALPix package) can be used to update or add FITS keywords to the header in Prim_stc and Exten_stc

Eric Hivon 2003-02-07