Random-surface-error efficiency (ε_rs) as a function of elevation (α) for the primary dish. ε_rs corresponds only to the large-scale deviations found by the OOF holography method. Each phase-error map was calculated with n = 5 and then the efficiency was computed using Eqs. (3) and (11). The dashed red line represents the traditionally defined value for a good efficiency, δ_rms ≤ λ/16 (ε_rs = 0.54). The labels L and B are azimuth and elevation single scans, and LB are the combination in the basket-weaving mode. Squares show observations from December 2019, triangles December 2020, circles February 2021, and diamonds March 2021.