Dependence of the dipole modulation amplitude as a function of ℓ_max. Upper panel: the amplitude of the dipole of the reconstructed power modulation from 143 × 217 GHz maps with the kinematic dipole subtracted; the dashed line shows that the observed signal decreases with ℓ_max in the same way as the rms value expected from simulations. Lower panel: corresponding confidence values for the observed dipole of the modulation power spectrum assuming it followed a chi-squared distribution; this shows the anomalous-looking results for ℓ_max ~ 60 and ℓ_max ~ 600 consistent with Planck Collaboration XXVII (2014), but that on smaller scales the observed signal is consistent with isotropy as expected from the scale-invariant constraint using ℓ_max = 2000 shown in Fig. 17.