Comparison between continuum-normalised ESPRESSO, HARPS, and UVES spectra of the z_abs = 1.1508 absorber towards HE 0515−4414. Upper panels: compare the ESPRESSO (blue) and UVES (orange) spectra, while lower panels: compare the ESPRESSO (blue) and HARPS (orange) spectra. In each panel, the upper, middle, and lower spectra correspond to the three different transitions indicated – Mg I λ2852, Fe II λ2600 and Mg II λ2796, respectively – offset by 10% in normalised flux for clarity. We note that the resolving powers (R) of the spectra are substantially different, but the differences between the spectra are minor, except for the features near 0 and 9 km s⁻¹ (see text). Right-hand panels: focus on this region, where the absorption is strongest (on a different velocity scale).