Planck 353 GHz angular power spectrum computed on M_B2 defined in Sect. 6.1 and extrapolated to 150 GHz (box centres). The shaded boxes represent the ± 1σ uncertainties: blue for the statistical uncertainties from noise; and red adding in quadrature the uncertainty from the extrapolation to 150 GHz. The Planck 2013 best-fit ΛCDM CMB model based on temperature anisotropies, with a tensor amplitude fixed at r = 0.2, is overplotted as a black line.