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This IDL facility provides a means to write into a FITS file as an ascii table extension a (beam) window function W(l) or W(l). Adds additional headers if required. The facility is primarily intended to allow the user to write an arbitrary window function 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/


IDL> BL2FITS, bl_array, fitsfile, [HDR = , /HELP, XHDR =]


real or double array of Bl coefficients to be written to file. This has dimension (lmax+1,n) with $1\le n \le 3$, given in the sequence T E B.
String containing the name of the file to be written.


String array containing the (non-trivial) primary header for the FITS file.
If set, a help message is printed out, no file is written

String array containing the (non-trivial) extension header for the FITS file.


bl2fits writes the input B(l) or W(l) 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/two/three column(s) are automatically named TEMPERATURE, GRAD, CURL respectively. If the window function is provided in a double precision array, the output format will automatically feature more decimal places.


This section lists the routines related to bl2fits

version 6.1 or more is necessary to run bl2fits.
provides the complimentary routine to read in a window function or power spectrum from a FITS file.
utilises the output file generated by bl2fits(option beam_file).


beam1 = gaussbeam(10., 2000, 1)
beam2 = gaussbeam(15., 2000, 1)
beam = (beam1 + beam2) / 2.
bl2fits, beam, 'beam.fits'

bl2fits writes the beam window function stored in the variable beam (=Legendre transform of a circular beam) into the output FITS file beam.fits.

Eric Hivon 2010-06-18
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