ALMA antennas at the AOS

Five 12-metre antennas at the ALMA Array Operations Site (AOS), located at 5000 metres altitude on the Chajnantor plateau. In this aerial picture, taken on 24 March 2011, the antennas are positioned on the pads of the Atacama Compact Array (ACA). When ALMA is complete, the ACA will be made up of four 12-metre antennas plus twelve 7-metre antennas, positioned near the centre of the main array. The main array will be composed of fifty 12-metre antennas.