Black line: averaged disk-integrated spectra of Mars between 1233.90 and 1234.10 cm⁻¹, obtained from the summation of the four spectra shown in Fig. 7. For the July 6 spectrum, a spike appeared at the position of the CO₂ line at 1233.93 cm⁻¹, so the averaged CO₂ line was obtained from the summation of the three other spectra. Synthetic models were calculated using the atmospheric parameters described in Sect. 3.1, with H₂O₂ = 0 ppbv (green line), 15 ppbv (red line), and 30 ppbv (blue line). H₂O₂ is undetected, with a 2σ upper limit of 15 ppbv. The spectral resolution of the models is 0.014 cm⁻¹.