First coordinated observations between Solar Orbiter and the Daniel K. Inouye Solar Telescope

¹ ETH-Zürich, Hönggerberg campus, HIT building, Wolfgang-Pauli-Str. 27, 8093 Zürich, Switzerland
² PMOD/WRC, Dorfstrasse 33, CH-7260 Davos Dorf, Switzerland
³ European Space Agency (ESA), European Space Research and Technology Centre (ESTEC), Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
⁴ National Solar Observatory, 22Ōhia Kū Street, Pukalani, HI 96768 USA
⁵ National Solar Observatory, 3665 Discovery Drive, Boulder, CO, 80303 USA
⁶ Université Paris–Saclay, CNRS, Institut d’astrophysique spatiale, 91405 Orsay, France
⁷ Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

^⋆ Corresponding author: krzysztof.barczynski@pmodwrc.ch

Received: 6 March 2025
Accepted: 23 June 2025

Abstract

Context. Solar Orbiter and the Daniel K. Inouye Solar Telescope (DKIST) are two of the newest facilities available to the solar physics community. The first coordinated observations of the Sun by these two facilities occurred over the course of one week in October 2022. The returned data are open-access and will provide a valuable resource to researchers in the field.

Aims. Here, we provide an overview of the datasets collected by Solar Orbiter and DKIST through this coordination and discuss their scientific potential. Our aim is to demonstrate how these unique high-resolution coordinated observations, as well as similar observations obtained through subsequent campaigns, can help tackle important science questions in the field.

Methods. A decayed active region (without NOAA number during our observation but identified as AR13110 during previous solar rotation) was simultaneously observed by Solar Orbiter and DKIST at specific times between 18 and 24 October 2022. Between these dates, the Solar Orbiter spacecraft moved from a position with a separation angle of 77° with Earth to a position with a separation angle of 51°, allowing stereoscopic observations to be collected with the ground-based telescope DKIST. From Solar Orbiter, observations are provided by the Extreme Ultraviolet Imager (EUI), Polarimetric and Helioseismic Imager (PHI), and the Spectral Imaging of the Coronal Environment (SPICE) instruments. Meanwhile, DKIST observed using the Cryogenic Near Infrared Spectropolarimeter (CryoNIRSP), the Visible Broadband Imager (VBI), and the Visible Spectropolarimeter (ViSP).

Results. Coordinated observations were successfully collected at several distinct times over the week. Despite the active region itself being in an advanced decayed phase, a range of interesting features are evident in the collected data. As such, a variety of research topics can be advanced using these observations. In this article, we focus on three specific topics as representative examples, namely, coronal loop physics, the formation and evolution of the small-scale active region brightenings, and coronal rain dynamics.

Conclusions. The first coordinated observation campaign conducted by both Solar Orbiter and DKIST was a success. These open-access observations, and others like them, should help the solar physics community tackle key questions in the field. Such stereoscopic coordinated observations open up a new era in the analysis of the solar atmosphere.