1. Inst. of Comput. & Network Eng., Tech. Univ. Braunschweig, Braunschweig, Germany
2. Astrium GmbH, Friedrichshafen, Germany
3. Fraunhofer-Inst. fur Angewandte Opt. und Feinmechanik IOF, Jena, Germany
4. Dept. of Phys., Univ. of Jyvaskyla, Jyvaskyla, Finland
5. ESA-ESTEC, Eur. Space Agency, Noordwijk, Netherlands