The synthetic spectrum of SO₂ and HDO on Venus between 1350.10 and 1350.45 cm^-1 (rest frequencies). Red: SO₂ = 25 ppb (upper curve) and 100 ppb (lower curve). Black: HDO = 1 ppm (upper curve) and 3 ppm (lower curve). For the SO₂ line at 1350.12 cm^-1, the line depths are 0.035 and 0.126 respectively; the departure from linearity is 11%. For the HDO line at 1350.26 cm^-1, the line depths are 0.025 and 0.070 respectively; the departure from linearity is 7%. Spectra are calculated with a mean airmass of 1.4.