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cl2fits
This IDL facility provides a means to
write into a FITS file as an ascii table extension the power
spectrum coefficients passed to the routine. Adds additional
headers if required. The facility is primarily intended to allow the
user to write a theoretical power spectrum into a FITS file in
the correct format to be ingested by the HEALPix simulation facility
synfast.
Location in HEALPix directory tree:
src/idl/fits/cl2fits.pro
FORMAT IDL>
CL2FITS, cl_array, fitsfile, [HDR = , /HELP, XHDR = , CMBFAST =, UNITS= ]
QUALIFIERS
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cl_array
- real or double array of Cl coefficients to be written to
file. This has dimension either (lmax+1,6) given in the sequence T E B
TxE TxB ExB or (lmax+1,4) given in the sequence T E B
TxE or (lmax+1) for T alone. The convention for the power spectrum is that it is not
normalised by the Harrison-Zeldovich (flat) spectrum.
-
fitsfile
- String containing the name of the file to be written.
KEYWORDS
-
HDR =
- String array containing the (non-trivial) primary header
for the FITS file.
-
/HELP
- If set, a help message is printed out, no file is written
-
XHDR =
- String array containing the (non-trivial) extension header
for the FITS file.
-
CMBFAST =
- if set, the routine will add the keyword 'POLNORM =
CMBFAST' in the FITS header, meaning that the polarization power spectra
have the same convention as CMBFAST (and Healpix 1.2).
If this keyword is not present in the input FITS file, synfast will issue a
warning when simulating a polarization map from that power spectrum, but no
attempt to renormalize the power spectra will be made. To actually perform
the renormalization, see convert_oldhpx2cmbfast
-
UNITS =
- String scalar containing units of power spectrum (eg, uK^2,
Kelvin**2, ...), to be put in keywords 'TUNIT*' of the extension header.
If provided, will override the values present in XHDR (if any).
-
- NOTE: optional header strings should NOT include the
header keywords explicitly written by this routine.
DESCRIPTION
cl2fits writes the input power spectrum coefficients into a FITS
file containing an ascii table extension. Optional headers conforming
to the FITS convention can also be written to the output file. All
required FITS header keywords (like SIMPLE, BITPIX, ...) are automatically generated by the
routine and should NOT be duplicated in the optional header inputs
(they would be ignored anyway).
The one/four/six column(s) are automatically named
TEMPERATURE, GRAD, CURL, G-T, C-T and C-G
respectively.
If the power spectrum is provided in a double precision array, the output format
will automatically feature more decimal places.
The current implementation is much faster than the one available in
Healpix 1.10 thanks to replacing an internal loop by vector operations.
RELATED ROUTINESThis section lists the routines related to cl2fits
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idl
- version 6.1 or more is necessary to run cl2fits.
-
fits2cl
- provides the complimentary routine to read in a
power spectrum from a FITS file.
-
convert_oldhpx2cmbfast
- convert an
existing power spectrum FITS file from the polarization convention used in
Healpix 1.1 to the one used in Healpix 1.2 (and CMBFAST).
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bl2fits
- facility to write a window function into a FITS file.
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fits2alm, alm2fits
- routines to read and write alm coefficients
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synfast
- utilises the output file generated by cl2fits.
EXAMPLE:
cl2fitswrites the power spectrum stored in the variable pwrsp
to the output FITS file spectrum.fits with optional headers
passed by the string variables hdr and xhdr.
Eric Hivon
2010-06-18
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