Velocity profiles from stacks of the [Fe X] λ6374.5 and [Fe XIV] λ5302.9 lines from a combined sample of 183/156 VLT/UVES and KECK/HIRES spectra (see Sect. 4.2). The resulting S/N per 20 km s⁻¹ pixel element is 900 for the stacked [Fe X] profile and 1240 for [Fe XIV]. In the profile of the [Fe X] line, a weak DIB is detected near +300 km s⁻¹. The positions of telluric features in the [Fe X] profile are indicated with the crossed circles (from Pettini et al. 1989). Note that the S/N ratios achieved here still are 1–2 orders of magnitude below the values predicted by our models (see Fig. 2).