Program: GN-2010B-Q-95

Uranus passed through its northern spring equinox in December 2007. Uranus' circulation and cloud structure was expected to change rapidly during this period due to changes in solar energy deposition as the northern hemisphere emerged into sunlight. Observations with UKIRT in 2006, 2007 and 2008 detected a clear change of the latitudinal and vertical cloud structure during this period, but the spatial resolution was limited by atmospheric seeing and the achievable S/N from a 3.8m telescope was only ~10 at some wavelengths. In 2009 observations at high spatial resolution (with adaptive optics) and high sensitivity were made with Gemini North, which showed that Uranus' appearance had changed still further. We here request time on Gemini North to extend this time series of measurements of Uranus' rapidly changing atmosphere into 2010. This data will enable us to interpret the existing data more completely, confirm the changes already seen, and will allow us to explore a further year's evolution of Uranus' rapidly changing atmosphere with unprecedented resolution and detail.