Cross-correlation analysis of WASP-121b’s UVES transmission spectra, using the model parameters reported by Evans et al. (2018). Left panels: analysis with the complete line list and the right panels use the reduced line list described in Sect. 2.4. Top panels: K_p-υ_sγs maps and the bottom panels show horizontal slices of these maps at the expected planet velocity K_p = 217 km s⁻¹ (dashed) and at the injection velocity K_p = −217 km s⁻¹ (solid).