Disk-integrated spectra of Venus between 1160 and 1163 cm⁻¹ (8.6 µm) recorded on July 14, 2023, October 7, 2023 and January 22, 2025. The positions of the strongest SO₂ lines are indicated in red by vertical dashed lines. The terrestrial lines coincide in the July 2023 and January 2025 because the Doppler shift is the same for both datasets, while it is different for the spectrum taken in October 2023. The spectra are dominated by terrestrial atmospheric absorption features, mostly N₂O and O₃. The black rectangle shows the spectral range used for our analysis.