Thomas Berkefeld, Alexander Bell, Reiner Volkmer, F. Heidecke, Tobias Preis, Thomas Sonner, E. Nakai, A. Lagg, A. Gandorfer, Sami K. Solanki, Jose Carlos del Toro Iniesta, Yukio Katsukawa, P. N. Bernasconi, A. Feller, T. L. Riethmüller, A. Álvarez‐Herrero, Masahito Kubo, Valentin Martinez Pillet, H. N. Smitha, D. Orozco Suárez, B. Grauf, Michael Carpenter
Abstract This paper describes the wave-front correction and image stabilisation system (CWS) developed for the Sunrise iii balloon-borne telescope, and provides information about its performance as measured during the integration into the telescope and during the 2024 science flight. The fast image stabilisation is done by a correlation tracker (CT) and a fast tip-tilt mirror, low order aberrations such as defocus and coma are measured by a six-element Shack-Hartmann wavefront sensor (WFS) and corrected by an active telescope secondary mirror for automated focus and manual coma correction. The CWS is specified to deliver a stabilised image with a precision of 0.005 arcsec (rms). The autofocus adjustment is specified to maintain a focus stability of 0.01 waves in the focal plane of the CWS.