WMAP Inverse Covariance Matrix for a Reduced Resolution, Single Year Q,U Map Per Differencing Assembly
FITS Header Information

The inverse covariance matrix is stored as an image in the primary header/data unit.

Primary Header

SIMPLE  =                    T /FITS format
BITPIX  =                  -32 /
NAXIS   =                    2 /Number of dimensions
NAXIS1  =                 6144 /
NAXIS2  =                 6144 /
EXTEND  =                    T /Extensions may be present
PIXTYPE = 'HEALPIX '           /Pixel algorigthm
ORDERING= 'NESTED  '           /Ordering scheme
RESOLUTN=                    4 /Resolution Index
NSIDE   =                   16 /Resolution Parameter
NPIX    =                 3072 /# pixels in associated maps
FREQ    = 'K band  '           /Frequency band
DA      = 'K1      '           /Differencing Assembly
RELEASE = 'DR4     '           /WMAP Release
TELESCOP= 'WMAP    '           /Wilkinson Microwave Anisotropy Probe
COMMENT This file contains the WMAP Polarization (Q and U) Res 4
COMMENT N-Inverse file for the differencing assembly indicated
COMMENT by the DA keyword.
COMMENT This is a 2Nx2N matrix, ordered (Q,U)
COMMENT The first year of data went into the map.
REFERENC= 'WMAP Explanatory Supplement:  http://lambda.gsfc.nasa.gov/' //lambda.
DATE    = '2010-04-09T00:41:16' /file creation date (YYYY-MM-DDThh:mm:ss UT)
STOKES  = 'QU      '           /
END

More information concerning the contents of this file is available.