Venus O2 night glow observations with VIRTSI/Venus Express

The oxygen nightglow emissions in the visible spectral range are known since the early observations with the Venera spacecrafts.Recent observations with the VIRTIS instrument on board Venus-Express allowed to re-detect the Herzberg II system of O 2 .In particular, the (0-7), (0-8), (0-9), (0-10), and (0-11) bands of the Herzberg II system have been observed in the limb data.These bands peak at about 95 km, with a mean total integrated intensity of about 200 kR.Moreover, 3 bands of the Chamberlain system, centred at 0.56 µm, 0.605 µm, and 0.657 µm were also detected.For the first time, the O 2 nightglow emissions were investigated simultaneously in the visible and in the IR spectral range, reporting a good agreement of the peak altitude values for the Herzberg II and the O 2 (a 1 Δ g -X 3 Σ - g ) band.Finally a 1-D atmospheric model was applied in order to interpret our results.The model, starting from realistic O and CO 2 vertical distribution, allows to well reproduce the observed profiles for the O 2 systems both in the visible and IR spectral ranges.