Atacama Pathfinder Experiment

Atacama Pathfinder Experiment (APEX) is a 12-metre millimetre and submillimetre radio telescope on the Llano de Chajnantor plateau in northern Chile at about 5,100 metres elevation. Its exceptionally dry atmosphere opens a window for studying cold gas and dust, star formation, galaxies and the distant Universe, while its instrumentation also serves as a test bed for new observing technology. APEX was inaugurated in 2005 and operates as an active research observatory with current facility instruments including nFLASH230, SEPIA345, nFLASH460 and SEPIA660; observations are normally carried out in service mode by APEX staff for accepted proposals from partner institutions. The APEX site publishes its base address in Ayllu de Sequitor, San Pedro de Atacama, but the telescope is at extreme altitude and is not a general walk-in visitor attraction; arrange scientific access through APEX and follow current high-altitude safety guidance.