Illustration of the procedure used to determine the H₂O column for each exposure (here exposure 0 and order 154) and the telluric H₂O removal. The mask of stellar lines, i.e., the BMT, is shown as a black dashed lines. The data and adjusted TAPAS transmittance are shown in black and light blue, respectively. The division of the data by the fit is shown in green. The correction works for isolated telluric lines and also for blended telluric and stellar lines (e.g., at 7240 A; see Fig. 5).