The European Solar Telescope

¹ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
³ Leibniz-Institut für Sonnenphysik (KIS), Schöneckstr. 6, 79104 Freiburg, Germany
⁴ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁵ Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 25165 Ondřejov, Czech Republic
⁶ Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden
⁷ Astronomical Institute of the Slovak Academy of Sciences, 05960 Tatranská Lomnica, Slovakia
⁸ Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast, BT7 1NN, Northern Ireland, UK
⁹ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
¹⁰ Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Penteli, Greece
¹¹ Laboratoire de Physique des Plasmas (LPP), École Polytechnique, IP Paris, Sorbonne Université, CNRS, Observatoire de Paris, Université PSL, Université Paris Saclay, Paris, France
¹² Rosseland Centre for Solar Physics, University of Oslo, PO Box 1029, Blindern 0315, Oslo, Norway
¹³ LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 5 place Jules Janssen, 92195 Meudon, France
¹⁴ University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Polo Universitario Lugano, Via Serafino Balestra 16, 6900 Lugano, Switzerland
¹⁵ GEPI, Observatoire de Paris, PSL Research University, CNRS, 92195 Meudon, France
¹⁶ INAF Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34143 Trieste, Italy
¹⁷ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
¹⁸ Instituto de Astrofísica e Ciências do Espaço, Universidade de Coimbra, OGAUC, Rua do Observatório s/n, 3040-004 Coimbra, Portugal
¹⁹ PMOD/WRC, Dorfstrasse 33, 7260 Davos Dorf, Switzerland
²⁰ ETH-Zurich, Hönggerberg campus, HIT building, Zürich, Switzerland
²¹ University of Applied Sciences Western Switzerland (HEIG-VD), 1, route de Cheseaux, 1401 Yverdon-les-Bains, Switzerland
²² Department of Electrical Engineering, Pontificia Universidad Católica de Chile, 4860 Vicuña Mackenna, 7820436 Santiago, Chile
²³ National Solar Observatory (NSO), 3665 Discovery Drive, Boulder, CO 80303, USA
²⁴ IRSOL – Istituto Ricerche Solari “Aldo e Cele Daccò”, Università della Svizzera italiana (USI), 6605 Locarno-Monti, Switzerland
²⁵ Euler Institute, Università della Svizzera italiana (USI), 6900 Lugano, Switzerland
²⁶ UCL Mullard Space Science Laboratory, Holmbury St Mary, Dorking RH5 6NT, UK
²⁷ Royal Observatory of Belgium, 1180 Ukkel, Belgium
²⁸ University of Wrocław, Centre of Scientific Excellence – Solar and Stellar Activity, Kopernika 11, 51-622 Wrocław, Poland
²⁹ Astronomical Institute, University of Wrocław, ul. Kopernika 11, 51-622 Wrocław, Poland
³⁰ Physics Department, University of Rome Tor Vergata, 00133 Rome, Italy
³¹ Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
³² Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kačićeva 26, 10000 Zagreb, Croatia
³³ IGAM/Institute of Physics, Karl-Franzens University Graz, Universitätsplatz 5/II, Graz, Austria
³⁴ Max-Planck-Institut für Sonnensystemforschung (MPS), Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
³⁵ Centre for Advanced Instrumentation, Department of Physics, Durham University, Durham, UK
³⁶ Department of Physics, University of Calabria, Ponte P. Bucci 31C, 87036 Rende, Italy
³⁷ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern 0315, Oslo, Norway
³⁸ GRANTECAN S.A., C/Vía Láctea s/n (IAC) 38205 La Laguna, Tenerife, Spain
³⁹ INAF Osservatorio Astrofísico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁴⁰ INAF – Fund. Galileo Galilei, Rambla Jose Ana Fernández Perez 7, 38712 Breña Baja (La Palma), Canary Islands, Spain
⁴¹ INAF – Istituto di Astrofísica e Planetologia Spaziali, 00133 Roma, Italy
⁴² Université Paul Sabatier, Observatoire Midi-Pyrénées, IRAP, Cnrs, Cnes, 14 ave. E. Belin, 31400 Toulouse, France
⁴³ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
⁴⁴ Armagh Observatory & Planetarium, College Hill, Armagh BT61 9DG N. Ireland, UK
⁴⁵ Solar Physics & Space Plasma Research Center (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, S3 7RH, UK
⁴⁶ ELTE Eötvös Loránd University, Institute of Geography and Earth Sciences, Department of Astronomy, Budapest, Hungary
⁴⁷ Hungarian Solar Physics Foundation (HSPF), Petőfi tér 3., Gyula 5700, Hungary
⁴⁸ INAF Osservatorio Astronomico di Roma, via Frascati 33, 00078 Monte Porzio Catone, Italy
⁴⁹ Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
⁵⁰ CITEUC – Center for Earth and Space Research of the University of Coimbra, Geophysical and Astronomical Observatory and Department of Mathematics of the University of Coimbra, Coimbra, Portugal
⁵¹ Subdireccion general de Internacionalización de la Ciencia e Innovación. Ministerio de Ciencia e Innovación. Paseo de la Castellana 162, planta 16 impares, 28046 Madrid, Spain
⁵² SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
⁵³ CNRS IRL2009 – THEMIS, Via Lactea s/n, 38205 La Laguna, Canary Islands, Spain
⁵⁴ MAX IV Laboratory, Lund University, Box 188, 221 00 Lund, Sweden
⁵⁵ CNR-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, Italy
⁵⁶ INAF – Osservatorio Astrofísico di Catania, Via S. Sofia 78, 95123 Catania, Italy
⁵⁷ Utrecht University, Department of Physics & Astronomy Postbus 80000, 3508TA Utrecht, The Netherlands
⁵⁸ Department of Optics, Palacky University Olomouc, 17. Listopadu 12, Olomouc, Czech Republic
⁵⁹ University of Geneva, 7, route de Drize, 1227 Carouge, Switzerland
⁶⁰ Department of Computer Science, Aalto University, PO Box 15400, 00076 Aalto, Finland
⁶¹ Dipartimento di Fisica e Astronomia, Università di Firenze, Florence, Italy
⁶² Univ Lyon, Univ Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574, 69230 Saint-Genis-Laval, France
⁶³ Faculty of Communication Sciences, Università della Svizzera Italiana, Lugano, Switzerland
⁶⁴ University of California Observatories, 1156 High St., Santa Cruz, CA 95064, USA
⁶⁵ INAF Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
⁶⁶ Expert Analytics AS, Møllergata 8, 0179 Oslo, Norway
⁶⁷ University of L’Aquila, Dept. of Physical and Chemical Sciences, Via Vetoio 48, 67100 Coppito (AQ), Italy
⁶⁸ Centre for mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven, 3001 Leuven, Belgium
⁶⁹ Institute of Physics, University of Maria Curie-Skłodowska, Pl. M. Curie-Skłodowska 5, 20-031 Lublin, Poland
⁷⁰ Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, Moscow 121205, Russia
⁷¹ Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
⁷² INAF – Istituto di Astrofísica Spaziale e Fisica Cosmica Via Alfonso Corti 12, 20133 Milano, Italy
⁷³ Centro de Rádio Astronomia e Astrofísica Mackenzie, Escola de Engenharia, Universidade Presbiteriana Mackenzie, São Paulo, Brazil
⁷⁴ School of Space Research, Kyung Hee University, Yongin, Gyeonggi 446-701, Republic of Korea
⁷⁵ ASI, Italian Space Agency, Via del Politecnico snc, 00133 Rome, Italy
⁷⁶ Institute for Particle Physics and Astrophysics, ETH Zurich, Switzerland
⁷⁷ National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
⁷⁸ Consejo Superior de Investigaciones Científicas, Spain
⁷⁹ The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, PR China
⁸⁰ Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, PR China
⁸¹ Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Via S. Sofia 78, 95123 Catania, Italy

Received: 26 April 2022
Accepted: 14 July 2022

Abstract

The European Solar Telescope (EST) is a project aimed at studying the magnetic connectivity of the solar atmosphere, from the deep photosphere to the upper chromosphere. Its design combines the knowledge and expertise gathered by the European solar physics community during the construction and operation of state-of-the-art solar telescopes operating in visible and near-infrared wavelengths: the Swedish 1m Solar Telescope, the German Vacuum Tower Telescope and GREGOR, the French Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires, and the Dutch Open Telescope. With its 4.2 m primary mirror and an open configuration, EST will become the most powerful European ground-based facility to study the Sun in the coming decades in the visible and near-infrared bands. EST uses the most innovative technological advances: the first adaptive secondary mirror ever used in a solar telescope, a complex multi-conjugate adaptive optics with deformable mirrors that form part of the optical design in a natural way, a polarimetrically compensated telescope design that eliminates the complex temporal variation and wavelength dependence of the telescope Mueller matrix, and an instrument suite containing several (etalon-based) tunable imaging spectropolarimeters and several integral field unit spectropolarimeters. This publication summarises some fundamental science questions that can be addressed with the telescope, together with a complete description of its major subsystems.