Atacama Pathfinder Experiment

The Atacama Pathfinder Experiment (APEX) is a radio telescope 5,100 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. The main dish has a diameter of 12 m and consists of 264 aluminium panels with an average surface accuracy of 17 micrometres (r.m.s.). The telescope was officially inaugurated on September 25, 2005.