The Atacama Large Millimeter/Submillimeter Array

TLDR

ALMA is an international radio telescope under construction in Chile’s Atacama Desert, positioned at 5000 m elevation to exploit the dry site’s excellent atmospheric transmission across 0.3–10 mm wavelengths. This paper outlines ALMA’s scientific drivers, technical challenges, and planned progress. ALMA comprises two arrays: a reconfigurable set of up to 64 12‑m antennas spanning 150 m to ~15 km, and a second array of four 12‑m plus twelve 7‑m antennas in two compact ~50 m configurations, delivering interferometric and total‑power data on gas and dust from the solar system to high‑redshift galaxies.

Abstract

The Atacama Large Millimeter/submillimeter Array (ALMA) is an international radio telescope under construction in the Atacama Desert of northern Chile. ALMA is situated on a dry site at 5000 m elevation, allowing excellent atmospheric transmission over the instrument wavelength range of 0.3 to 10 mm. ALMA will consist of two arrays of high-precision antennas. One, of up to 64 12-m diameter antennas, is reconfigurable in multiple patterns ranging in size from 150 meters up to ~15 km. A second array is comprised of a set of four 12-m and twelve 7-m antennas operating in one of two closely packed configurations ~50 m in diameter. The instrument will provide both interferometric and total-power astronomical information on atomic, molecular and ionized gas and dust in the solar system, our Galaxy, and the nearby to high-redshift universe. In this paper we outline the scientific drivers, technical challenges and planned progress of ALMA.