This is the number of ALMA antennas that have completed Assembly, Integration and Verification at the Operations Support Facility (OSF) at 2,900 meters altitude, and then been transported to the 5,000 meter high Array Operations Site (AOS) on the Chajnantor plateau. The number of antennas presently at the AOS is lower than this number, as antennas are brought back down to the OSF when necessary for repairs and for regular maintenance.