The AT20G Survey is a blind 20 GHz survey of the entire southern sky with |b|>1.5o. Observations were carried out using the Australia Telescope Compact Array (ATCA) from 2004-2008. The final AT20G catalogue consists of 5890 sources above a 20 GHz flux density limit of 40 mJy and includes near-simultatneous observations at 4.8 and 8.6 GHz for most sources south of -15o.
A full description of the survey and resulting catalogue is presented in the source catalogue paper: Murphy, T. et al. 2010, MNRAS, 402, 2403. A detailed analysis of the AT20G sample is presented in Massardi, M. et al., 2011, MNRAS, 412, 318.