Likelihood posterior on r biases (with respect to an input signal of r = 0) for the different cases of combined calibration errors (presented in Sect. 2) from 10 000 Monte Carlo simulations as a function of the combined error on the angle Δψ_Gal in degrees. They are computed independently for the recombination bump (30 <  ℓ <  300, squares), the reionisation bump (2 <  ℓ <  30, diamonds), and the combination of both (2 <  ℓ <  300, crosses). The best-fit power laws are displayed as dashed, dash-dotted, and dash-double-dotted black lines.