Optical measurements of space debris in GEO

Optical astronomy has been revolutionized by the use of solid state CCD sensors. The introduction of these detectors opened new prospects for the automatic detection of faint moving objects like small asteroids and comets. Similar techniques may be used to observe artificial satellites and space debris. The detection limit of optical observations depends-apart from the apparent brightness - on the apparent motion of the objects. The technique therefore performs best for slow moving objects at high altitude orbits. In the geostationary ring (GEO) and in the geostationary transfer orbit region (GTO) optical techniques outperform radar observations in terms of minimum detectable object size, even when using telescopes of moderate size. Automated surveys ask for carefully planned observation scenarios as well as real-time (or 'near-real-time') processing of the acquired data. We present different observation and processing techniques including the determination of first orbits. The discussed techniques will be illustrated by preliminary results from two test campaigns conducted with the 1 m Zimmerwald Laser and Astrometry Telescope (ZIMLAT).