The conceptual design of the 50-meter Atacama Large Aperture Submillimeter Telescope (AtLAST)

¹ European Southern Observatory, Karl-Schwarzschild-Str. 2, Garching 85748, Germany
² Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL, 60637, USA
³ OHB Digital Connect, Weberstraße 21, 55130 Mainz, Germany
⁴ Independent Consultant, Kirchgasse 4, 61184 Karben, Germany
⁵ Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, 0315 Oslo, Norway
⁶ Instituto de Astrofísica and Centro de Astro-Ingeniería, Facultad de Física, Pontificia Universidad Católica de Chile, Santiago, Chile
⁷ UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
⁸ Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA, 19104, USA
⁹ Department of Technology Systems, University of Oslo, Gunnar Randars Vei 19, 2007 Kjeller, Norway
¹⁰ Department of Physics, Cornell University, Ithaca, NY 14853, USA
¹¹ Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
¹² INAF – Osservatorio Astronomico di Cagliari, 09047 Selargius, Italy
¹³ European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
¹⁴ Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
¹⁵ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹⁶ Departamento de Física de la Tierra y Astrofísica e Instituto de Física de Partículas y del Cosmos (IPARCOS). Universidad Complutense de Madrid, Av. Complutense, s/n, Ciudad Universitaria, 28040 Madrid, Spain

^★ Corresponding author; tonym@eso.org

Received: 28 February 2024
Accepted: 14 January 2025

Abstract

The (sub)millimeter sky contains a vast wealth of information that is both complementary and inaccessible to other wavelengths. Over half the light we receive is observable at millimeter and submillimeter wavelengths, yet we have mapped only a small portion of the sky at sufficient spatial resolution and sensitivity to detect and resolve distant galaxies or star-forming cores within their large- scale environments. For decades, the astronomical community has highlighted the need for a large, high-throughput (sub)millimeter (λ ~ 0.35–10 mm) single dish. The Atacama Large Aperture Submillimeter Telescope (AtLAST), with its 50-m aperture and 2° maximal field of view, aims to be such a facility. We present here the preliminary design concept for AtLAST, developed through an EU Horizon 2020-funded design study. Our design approach begins with a long lineage of (sub)millimeter telescopes, relies on calculations and simulations to realize the optics, and uses finite element analysis to optimize the conceptual designs for the mechanical structure and subsystems. The demanding technical requirements for AtLAST, set by transformative science goals, have motivated the design effort to combine novel concepts with lessons learned from previous efforts. The result is an innovative rocking chair design with six instrument bays, two of which are mounted on Nasmyth platforms, inside a large receiver cabin. Ultimately, AtLAST aims to achieve a surface accuracy of a ≤20 µm root mean square half wavefront error, corresponding to the goal of a Ruze efficiency of >50% at 950 GHz. We conclude that a closed-loop metrology of the active primary surface will be required to achieve our surface accuracy goal. In the next phase of the project, we shall prototype and test such a metrology on existing platforms, with the goal of delivering a mature, construction-ready design by the end of this decade.