RV computation of a representative individual line. The dashed grey vertical line represents the wavelength of the line l in the line list, as measured in the spectrum template (black dots, in this example, λ_tpl,l = 7096.4675 Å). The dash-dotted red vertical line represents the wavelength of the line l measured in an observation (black squares) with a Gaussian fit to the line (solid red line, in this example, λ_obs,l = 7096.4761 Å). The shaded grey region marks the data points considered in the Gaussian fit to the spectrum. The Doppler shift computed with Eq. (1) in this case is of 363 m s⁻¹.