All-sky Mollweide display of the Stokes maps (top) and (bottom) at 353 GHz after background subtraction. The regions of low polarization signal at high Galactic latitude are masked. These images include a grid of Galactic coordinates in degrees. The map shown in the bottom panel represents the Stokes U parameter in HEALPix convention, which corresponds to −U in IAU convention, as described in Eq. (1).