CMB pseudo power spectra for the three types of primordial power spectra. The solid blue line shows the pseudo spectrum based on a primordial spectrum with n_s = 0.972 and α_s = 0. The light blue crosses show one simulation of this spectrum, computed from the map in Fig. 1. The red line shows the pseudo spectrum for a primordial spectrum with n_s = 0.972 and α_s = − 0.017 and the orange line corresponds to a power spectrum with a localised feature at k = 0.03 Mpc^-1. These spectra include the effects of the mask, the 15 arcmin beam, the HEALPix window for nside of 1024, and the instrumental noise power spectrum, which is shown by a solid black line.