The Daniel K. Inouye Solar Telescope – Observatory Overview
Authors: Rimmele Thomas R. , Warner Mark , Keil Stephen L. , Goode Philip R. , Knölker Michael , Kuhn Jeffrey R. , Rosner Robert R. , McMullin Joseph P. , Casini Roberto , Lin Haosheng , Wöger Friedrich , von der Lühe Oskar , Tritschler Alexandra , Davey Alisdair , de Wijn Alfred , Elmore David F. , Fehlmann André , Harrington David M. , Jaeggli Sarah A. , Rast Mark P. , Schad Thomas A. , Schmidt Wolfgang , Mathioudakis Mihalis , Mickey Donald L. , Anan Tetsu , Beck Christian , Marshall Heather K. , Jeffers Paul F. , Oschmann Jacobus M. , Beard Andrew , Berst David C. , Cowan Bruce A. , Craig Simon C. , Cross Eric , Cummings Bryan K. , Donnelly Colleen , de Vanssay Jean-Benoit , Eigenbrot Arthur D. , Ferayorni Andrew , Foster Christopher , Galapon Chriselle Ann , Gedrites Christopher , Gonzales Kerry , Goodrich Bret D. , Gregory Brian S. , Guzman Stephanie S. , Guzzo Stephen , Hegwer Steve , Hubbard Robert P. , Hubbard John R. , Johansson Erik M. , Johnson Luke C. , Liang Chen , Liang Mary , McQuillen Isaac , Mayer Christopher , Newman Karl , Onodera Brialyn , Phelps LeEllen , Puentes Myles M. , Richards Christopher , Rimmele Lukas M. , Sekulic Predrag , Shimko Stephan R. , Simison Brett E. , Smith Brett , Starman Erik , Sueoka Stacey R. , Summers Richard T. , Szabo Aimee , Szabo Louis , Wampler Stephen B. , Williams Timothy R. , White Charles 
Published: December 2020

We present an overview of the National Science Foundation’sDaniel K. Inouye Solar Telescope(DKIST), its instruments, and support facilities. The 4 m aperture DKIST provides the highest-resolution observations of the Sun ever achieved. The large aperture of DKIST combined with state-of-the-art instrumentation provide the sensitivity to measure the vector magnetic field in the chromosphere and in the faint corona, i.e. for the first time with DKIST we will be able to measure and study the most important free-energy source in the outer solar atmosphere – the coronal magnetic field. Over its operational lifetime DKIST will advance our knowledge of fundamental astronomical processes, including highly dynamic solar eruptions that are at the source of space-weather events that impact our technological society. Design and construction of DKIST took over two decades. DKIST implements a fast (f/2), off-axis Gregorian optical design. The maximum available field-of-view is 5 arcmin. A complex thermal-control system was implemented in order to remove at prime focus the majority of the 13 kW collected by the primary mirror and to keep optical surfaces and structures at ambient temperature, thus avoiding self-induced local seeing. A high-order adaptive-optics system with 1600 actuators corrects atmospheric seeing enabling diffraction limited imaging and spectroscopy. Five instruments, four of which are polarimeters, provide powerful diagnostic capability over a broad wavelength range covering the visible, near-infrared, and mid-infrared spectrum. New polarization-calibration strategies were developed to achieve the stringent polarization accuracy requirement of 5×10−4. Instruments can be combined and operated simultaneously in order to obtain a maximum of observational information. Observing time on DKIST is allocated through an open, merit-based proposal process. DKIST will be operated primarily in “service mode” and is expected to on average produce 3 PB of raw data per year. A newly developed data center located at the NSO Headquarters in Boulder will initially serve fully calibrated data to the international users community. Higher-level data products, such as physical parameters obtained from inversions of spectro-polarimetric data will be added as resources allow.