Reconstructions of the Faraday sky. Panel a: our main result, the posterior mean of reconstruction I. This map uses the free–free EM map as a proxy for the Faraday amplitude. The model also contains fields that translate the free–free map into a Faraday amplitude, thereby balancing effects that support and those that disturb a direct relation of these two quantities. Panel b: posterior mean of reconstruction II, without additional free–free data. Panel c: posterior mean of the (NO15) reconstruction. The differences in the three maps are shown in Fig. 2. These maps and all maps following in this paper are presented in Galactic coordinates centered at (l, b) = (0°, 0°). The results are available online.