Wilkinson Microwave Anisotropy Probe DR4
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DR4 Loss Imbalance Templates
HEALPix, nested, res 4 (Nside=16)
WMAP data processing takes into account the small transmission imbalance between the A side and the B side of the instrument. The imbalance has been measured for each radiometer using WMAP flight data, with an uncertainty of 20%. This uncertainty could lead to significant artifacts in the polarization skymaps. Spatial patterns in the Stokes Q and U maps that correspond to this uncertainty have been determined by comparing results of data simulations in which the transmission imbalance factors have been varied. See section 2.9 of Jarosik et al. (2010). In one case, a simulation with these factors increased by 20% for both radiometers in each DA was compared with a simulation using nominal values. In a second case, the imbalance was increased by 10% for radiometer 1 and decreased by 10% for radiometer 2 in each DA. This yielded two sets of Q,U templates, which we provide as HEALPix Nside=16 (Res 4) maps in mK for each DA. Section 3.5.1 of Jarosik et al. (2007) describes how these templates can be projected out of the inverse covariance matrices so that transmission imbalance uncertainty will not affect subsequent analyses. The calculation is done using