Top: comparison between the measured and estimated ratios of the a_ℓm harmonic coefficients for the nominal maps (produced using the full knowledge of the beam B over the 4π sphere) and the maps produced under the assumption of a pencil beam. The estimate has been computed using Eq. (11). Bottom: difference between the measured ratio and the estimate. The agreement is better than 0.03% for all 22 LFI radiometers.