Spectrum of R Leo in the spectral range 701−742 cm⁻¹ in the rest frequency (i.e., we have corrected for R Leo’s radial velocity with respect to Earth at the time of observation). The detected CO₂ lines are plotted in different colors depending on the band. The red synthetic spectrum is a model to the CO₂ emission (Sect. 4). The gray spectrum is the atmospheric transmission calculated with the ATRAN code (Lord 1992). Only the lines that were clearly detected are marked with arrows. The branches are not indicated for the sake of clarity. An additional spectral range is shown in Fig. B.1.