Atacama Large Millimeter Array (Alma)

alma_01The Atacama Large Millimeter Array (ALMA) is an international astronomy facility. ALMA is an equal partnership between Europe and North America, in cooperation with the Republic of Chile, and is funded in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC), and in Europe by the European Southern Observatory (ESO) and Spain. ALMA construction and operations are led on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI), and on behalf of Europe by ESO. Japan has joined ALMA as a third partner, bringing the Atacama Compact Array (ACA) and additional receiver bands for both arrays, to form Enhanced ALMA.

Text and Photo:
European Southern Observatory

ALMA” the Atacama Large Millimeter Array” will be a single instrument composed of 66 high-precision antennas located on the Chajnantor plain of the Chilean Andes in the District of San Pedro de Atacama, 5,000 meters (16,500 feet) above sea level. ALMA™s primary function will be to observe and image with unprecedented clarity the enigmatic cold regions of the Universe, which are optically dark, yet shine brightly in the millimeter portion of the electromagnetic spectrum.

To bolster ALMA’s sensitivity on scales between the antenna diameter of 12 m and the shortest baseline of 15 m the ACA, comprised of four 12 m telescopes along with twelve 7m antennas, built and equipped to the same specifications as those in the main array, will be contributed by Japan as part of its entry into the project. Japan is providing a separate signal correlator for the ACA similar in power to that of the large array. In addition, Japan is providing two additional receiver bands for all 80 antennas in Enhanced ALMA.

ALMA consists of an array of sixty-four 12m antennas with reconfigurable baselines ranging from 150 m to 18 km. The ability to reconfigure provides a zoom lens capability, allowing a resolution as fine as 0.01″, a factor of five better than the Hubble Space Telescope Advanced Camera for Surveys. ALMA is designed to operate at wavelengths of 0.3 to 9 millimeters where the Earth™s atmosphere above a high, dry site is largely transparent and where clouds of cold gas as close as the nearest stars and as distant as the observable bounds of the universe all have their characteristic spectral signatures. It will provide scientific insight at wavelengths complementary to those of the Very Large Array and Gemini and with the same image detail and clarity. ALMA is the complete imaging, spectroscopic instrument for the millimeter/submillimeter.

ALMA is currently under development.