Upper: map of the apparent magnetic field (⟨ B_⊥ ⟩) orientation. The polarization segments from the measured 353 GHz polarization, having been rotated by 90°, show the orientation of the apparent magnetic field, but their length is constant, not reflecting the changing polarization fraction. The colour map shows the 353 GHz emission in log ₁₀ scale and ranges from 10^-2 to 10 MJy sr^-1. Lower: map of the 353 GHz polarization angle uncertainty (σ_ψ) at 1° resolution. The scale is linear from σ_ψ = 0° to σ_ψ = 52.3°. The polarization angle is obtained using the Bayesian method with a mean posterior estimator (see Sect. 2.3). The uncertainty map includes statistical and systematic contributions. The same mask as in Fig. 1 is applied.