Blue curve: TEXES spectrum recorded on March 28, 2015, between 954 and 956 cm⁻¹, integrated for all airmasses lower than 1.7. Black curve (shifted by −0.2 for clarity): TEXES disk-integrated spectrum of Venus, extracted from the same data set, including the limb contribution. Red curve (shifted by −0.4 for clarity): synthetic spectrum, including CO₂ and PH₃, with a volume mixing ratio of 20 ppbv, constant with altitude, calculated for an airmass of 1.15 (30° latitude). The broad absorption feature around 955.215 cm⁻¹ is due to a telluric water vapor line. The red ticks at the top of the figure indicate the discontinuities due to an overlap between two consecutive orders.