Impact of the number of lines selected in the telluric model. Top panel: average water telluric line built for the model, with line intensity thresholds at 10⁻²⁴, 10⁻²⁵, 10⁻²⁶, 10⁻²⁷, 10⁻²⁸, and 10⁻²⁹ cm⁻¹/(molecule cm⁻²). Middle panel: residuals of the average lines with respect to including all the lines. See Sect. 3 for more details on how the average line is built. Bottom panel: zoom on the residuals obtained with the model that includes the 10⁻²⁶, 10⁻²⁷, 10⁻²⁸ cm⁻¹/(molecule cm⁻²) strongest water lines. The dispersion and P2V amplitude of the residuals are reported in the legend.