2006 (IPP)

Browse

Now showing 1 - 1 of 1

Non-circular beam correction to the CMB power spectrum
(2006-08-24) Souradeep, Tarun; Mitra, Sanjit; Sengupta, Anand; et al.
In the era of high precision CMB measurements, systematic eﬀects are beginning to limit the ability to extract subtler cosmological information. The non-circularity of the experimental beam has become progressively important as CMB experiments strive to attain higher angular resolution and sensitivity. The eﬀect of non-circular beam on the power spectrum is important at multipoles larger than the beam-width. For recent experiments with high angular resolution, optimal methods of power spectrum estimation are computationally prohibitive and sub-optimal approaches, such as the Pseudo-Cl method, are used. We provide an analytic framework for correcting the power spectrum for the eﬀect of beam non-circularity and non-uniform sky coverage (including incomplete/masked sky maps). The approach is perturbative in the distortion of the beam from non-circularity allowing for rapid computations when the beam is mildly non-circular. When non-circular beam eﬀect is important, we advocate that it is computationally advantageous to employ ‘soft’ azimuthally apodized masks whose spherical harmonic transform die down fast with m.