  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.
