Transmission spectra map of HD 189733 b around the sodium doublet (co-added and both transits combined) after POLDs correction using synthetic models on individual spectra in the planetary rest frame (see Fig. D.1 for the uncorrected version). The dashed dark purple line indicates the sodium planetary rest velocity, and the horizontal dashed lines show the transit contacts T₁, T₂, T₃, and T₄ from bottom to top.