Optimising the Use of the European Solar Telescope before MCAO: the Multi-Aperture Option

Göran Scharmer

Hosted by Stockholm University, Institute for Solar Physics, SE on January 29, 2026

Abstract

We discuss how to optimise the science output of the European Solar Telescope (EST), when used without the wide-field compensation for high-altitude seeing that the EST multi conjugate adaptive optics (MCAO) will offer. This will likely be the mode of operating EST during its first year, following first light. In this mode, the spatial resolution of a much smaller telescope could surpass that of EST. We propose to operate EST in multi-aperture mode, which will, together with the use of short exposure times and image reconstruction techniques, dramatically improve image quality. In particular, the multi-aperture mode will provide the sustained stable high image quality needed for obtaining time sequences of spectropolarimetric data. The multi-aperture mode is implemented by optically segmenting the 4.2 m aperture into six 1.4 m subapertures by a low-cost modification of the camera lenses of the three Fabry-Perot systems that are expected to be operational soon after first light.