The optical design of the European Solar Telescope successfully evaluated

The Sun is the almost exclusive source of energy for life on our planet, it is decisive for the Earth's climate, it is the basic model for all stellar astrophysics. Therefore, it is crucial to study the Sun in order to understand its behaviour, its evolution and, above all, its influence on Earth, life and human civilisation.

With its 4.2-metre primary mirror aperture, the European Solar Telescope (EST) will be in the next decade Europe's largest solar telescope and will to obtain high-resolution images of the Sun and information about our star, its surface phenomena, and its magnetic field. The scientific spin-offs will be enormous, but the technological and economic ones will also be important, as the funding countries will benefit from industrial orders and technological know-how.

Ambitious scientific projects such as EST require rigorous analysis and investigation at every stage of realisation. Therefore, about a month ago, the engineers designing EST submitted all the documentation on the telescope's optical design, including adaptive optics, to an independent international committee of experts in development of large telescopes and instrumentation for solar observation. The committee was tasked to rigorously examine and evaluate the design. On 10 and 11 October, a discussion between a team of engineers and the experts took place at the headquarters of the Instituto de Astrofísica de Canarias (IAC) which leads the EST project. At the end of the discussions, the experts presented a report in which they praised the work done and endorsed the project. This is one of the crucial milestones that EST has passed towards its final realization.

Switzerland has been involved in the EST project from the very beginning. Indeed, the Università della Svizzera italiana is a founding member of the EST Foundation, with IRSOL's director Prof. Svetlana Berdyugina appointed as a trustee on the Foundation Board and elected as a member of its Executive Committee. IRSOL will contribute to EST with its expertise in high-precision polarimetry, the area that IRSOL leads for several decades thanks to the continued developments of the most precise solar polarimeter in the world ZIMPOL. In addition, both USI, IRSOL as well as other Swiss scientific institutes together with their EST partners are aiming to complete necessary funding and construct EST at the Roque de los Muchachos Observatory on La Palma, Canary Islands.