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WMAP 28 TT Cross-Power Spectra
A cross-power spectrum is an angular power spectrum computed using the quadratic estimator on maps from two different differencing assemblies. Since the noise between the two different maps is uncorrelated, an unbiased estimate of the underlying power spectrum is achieved.
In order to minimize contamination from foregrounds signals, a Galactic foreground model was subtracted from the maps prior to computing the cross-power spectra, and a masking cut applied to high intensity regions of the Galactic plane. The foreground model was computed using a linear combination of map templates representing synchrotron, free-free, and dust components.
Cross-power spectra obtained from all 28 combinations of the 8 differencing assemblies Q1-W4 are provided. These 28 cross-power spectra form the basis of the WMAP combined TT power spectrum, which is the best estimate power spectrum.
The data product file, in FITS format, contains 28 binary table extensions, one for each of the 28 cross-power spectra. Each extension is named according to the differencing assembly combination used for that spectrum. Cross-power spectra are in units of uK2.
More details can be found in: