Comparison of the Planck and WMAP-9 power spectra. The green points show the combined WMAP-9 V+W-band spectrum computed on the same mask used for the 100 × 100 GHz Planck spectrum (with a combined WMAP+Planck mask for point sources) after rescaling the WMAP power spectrum by a multiplicative factor of 0.974. The magenta points show the Planck100 × 100 GHz spectrum computed on the same mask. The red line shows the best-fit Planck+WP+highL base ΛCDM model. The lower panel shows the residuals with respect to this model. The error bars on the WMAP points show the instrumental noise together with the noise-signal errors as discussed in the text; errors are not shown for Planck.