Abstract
ALMA (Atacama Large mm/sub-mm Array) is the state-of-the-art radiotelescope under construction at the 5000 m high plateau of Chajnantor in Chile. It is aimed to probe the universe at millimetre and submillimetre wavelength radiation (0.3 to 9.6 mm) to investigate mainly the cool Universe, molecular gas and dust, star formation, proto-planets, galaxies, cosmology etc. ALMA will consist initially of 66 high-precision antennas. The main array will have fifty antennas of 12 meters in diameter, acting together as an interferometer and a compact array (ACA) of four 12-metre and twelve 7-metre antennas. The antennas can be spread across the desert plateau over distances from 150 meters to 16 kilometers, which will give ALMA a variable angular resolution and sensitivity. The commissioning of ALMA started at the beginning of 2010. ALMA's construction is expected to be completed around 2012 but early scientific observations with a partial array will begin by the end of 2011.
