M. Tegmark et A. De Oliveira-costa, How to measure CMB polarization power spectra without losing information -art. no. 063001, PHYS REV D, 6406(6), 2001, pp. 3001
We present a method for measuring CMB polarization power spectra given inco
mplete sky coverage and test it with simulated examples such as Boomerang 2
001 and MAP. By augmenting the quadratic estimator method with an additiona
l step, we find that the E and B power spectra can be effectively disentang
led on angular scales substantially smaller than the width of the sky patch
in the narrowest direction. We find that the basic quadratic and maximum-l
ikelihood methods display an unneccesary sensitivity to systematic errors w
hen T-E cross-correlation is involved. and show how this problem can be eli
minated at negligible cost in increased error bars. We also test numericall
y the widely used approximation that sample variance scales inversely with
sky coverage, and find it to be an excellent approximation on scales substa
ntially smaller than the sky patch.