Atacama Pathfinder Experiment
The Atacama Pathfinder Experiment (APEX) is a radio telescope 5,104 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama Desert in northern Chile, 50 km east of San Pedro de Atacama built and operated by three European research institutes. The main dish has a diameter of 12 m and consists of 264 aluminium panels with an average surface accuracy of 17 micrometres (rms).
Source: Wikipedia — Atacama Pathfinder Experiment (CC BY-SA 4.0)