Full-sky RM maps in Mollweide (left) and orthographic projections centered at the galactic poles (right) for our reference case (setup A). The RM signal is internally computed by POLARIS and is obtained using the entire data cube. These maps are addressed in the text as the reference map. Dashed circles indicate the most prominent features corresponding to the regions highlighted in Fig. 2. Marked positions (green diamonds) correspond to minimal RM and maximal RM, respectively, of the total map.