Atacama Large Millimeter Array

The Atacama Large Millimeter Array (ALMA, aka Atacama Large Millimeter/Submillimeter Array) is an interferometer array of millimeter/submillimeter telescopes at the Chajnantor Plateau in the Atacama Desert in Chile. It was constructed and is operated by an international collaboration including significant American, Asian, and European participation. Its frequency-range spans the threshold between radio and infrared and it uses variants on radio-interferometry techniques adapted to the high frequencies. It sits at an altitude of 5000 meters and consists of 66 12-meter and 7-meter movable dishes that observe millimeter and sub-millimeter wavelengths. It began operation in 2013 with 50 12-meter dishes, having been under construction since 2003. A later addition called the Atacama Compact Array (ACA or Morita Array) consists of sixteen additional 12-meter and 7-meter dishes grouped within a smaller area that gives the group the ability to discern larger features. ALMA is currently produces among the most detailed images of many phenomena (within its wavelength-range) with angular resolutions varying down to less than fifteen milliarcseconds.