The Wave-Front Correction System for the Sunrise Balloon-Borne Solar Observatory

TL;DR

This paper details the wave-front correction system for the Sunrise balloon telescope, achieving high image stability and quality during its 5.5-day flight through a combination of sensors and active mirrors.

Contribution

It introduces a wave-front correction system with a Shack-Hartmann sensor and active mirrors, demonstrating effective in-flight image stabilization for a balloon-borne solar observatory.

Findings

Achieved 0.04 arcsec image stabilization precision

Maintained focus stability of 0.01 waves

Provided good image quality during 33 hours of flight

Abstract

This paper describes the wave-front correction system developed for the Sunrise balloon telescope, and provides information about its in-flight performance. For the correction of low-order aberrations, a Correlating Wave-Front Sensor (CWS) was used. It consisted of a six-element Shack-Hartmann wave-front sensor (WFS), a fast tip-tilt mirror for the compensation of image motion, and an active telescope secondary mirror for focus correction. The CWS delivered a stabilized image with a precision of 0.04 arcsec (rms), whenever the coarse pointing was better than 90 arcsec peak-to-peak. The automatic focus adjustment maintained a focus stability of 0.01 waves in the focal plane of the CWS. During the 5.5 day flight, good image quality and stability was achieved during 33 hours, containing 45 sequences that lasted between 10 and 45 minutes.