Multi-observatory observations of night-side of Venus at 2.3 micron - atmospheric circulation from tracking of cloud features

Abstract

Observations of Venus were made during 3 May to 11 May 2004 (117.4o - 125.7o phase angle) and 3 July to 10 July, 2004 (132.5o - 125.1o phase angle) from the 1.2-metre Mt. Abu Telescope at Gurushikhar, Himalayan Chandra Telescope at Mt. Saraswati, Hanle and the Nordic Optical Telescope at La Palma, Canary Islands and the NASA/Infra Red Telescope Facility (IRTF) at Mauna Kea, Hawaii in J and K bands. While the sunlit crescent portion was saturated in the detector, the night-side shows discrete cloud features. These features are seen to evolve over time and are markers of the atmospheric flow at tilda 53 km altitude above the surface. By combining multi-site observations, we are able to make measurements of zonal cloud velocities over baselines that are several hours long and get a better idea of the evolution of the features over time