Velocity slices through the Galactic component of the Na i D₁ absorption in the UVES spectra, using a “rainbow” intensity scale (with absorption increasing from purple/blue, through green/yellow to red; the intensity scale has the same range in both panels but it is centered on the median value in each panel). The velocity ranges are 7 and 15 km s^-1 for the slices centered at 9 and 24 km s^-1, respectively.