Notes. The error in the solid angle σ_Ω comes from the scanning beam error budget. The spatial variation ΔΩ is the RMS variation of the solid angle across the sky. Two values are reported for the FWHM: the first is the FWHM of the Gaussian whose solid angle is equivalent to that of the effective beams; the second in parenthesis is the mean best-fit Gaussian. Ω₁ and Ω₂ are the solid angles contained within a ring with radius 1 and 2 FWHM respectively (used for aperture photometry as described in Appendix A of Planck Collaboration XXVIII 2014). The ellipticity ϵ is the ratio of the major to minor axis of the best fit Gaussian, averaged over the full sky. Δϵ is the RMS variability over the sky of the ellipticity.