Map of the difference in mean RV between the previous Z14 map and the new one presented here (Z14 – New). The markers follow the same convention as in Fig. 1, but we only show the positions of the new data to highlight the regions where the updated map is better constrained. The new mean RV map is more symmetric and smoother than that of Z14, the asymmetry in the difference map reflects that. The largest differences appear within the inner 2° near the Galactic plane, where most of the new data are located.