|
CCD - General description
Optical observations have been playing an essential role at the Astronomical Institute of the University of Bern (AIUB) since its establishment in 1922. Such observations were first performed at the Muesmatt observatory, then at the Zimmerwald observatory (built 1956 by Prof. Max Schürer). The Zimmerwald observatory was extensively used for astrometric purposes. More than 100 asteroids and a hand full of comets (among them the comet Wild-II, the target of the NASA stardust mission) were discovered in Zimmerwald and named by the discoverer.
The 1-m telescope of the Zimmerwald observatory, inaugurated in 1997, was also designed as an astrometric telescope using the CCD-technique (Charge-Coupled Device). AIUB's astrometry group made extensive use of this facility to develop, as a broad-band facility, an astrometric observation technique, in particular for observing fast moving objects like artificial Earth satellites, space debris, Near Earth Asteroids (NEAs), etc.
The astrometry group of the AIUB today has a world-leading position in the domain of CCD-Astrometry applied to fast moving objects. This is underlined by the fact that the group developed the software system for ESA's Space Debris Telescope on the island of Tenerife (1-m Zeiss-telescope at the Teide Astrophysical Observatory). Survey campaigns performed at Tenerife, planned jointly by ESA and AIUB, and processed at AIUB using the software developed and maintained by the group, significantly improved the knowledge of the space debris population, in particular in the so-called geostationary belt. In this context the ESA studies "Geostationary Orbit Objects Survey" and "Geostationary Transfer Orbit Survey" were completed in 2004 and 2006 respectively with the publication of the final report. In 2003 a new population of debris objects in an orbital region were no potential parent object could be identified. The population has its origin in the geostationary orbit and is characterized by very high values of the area-to-mass ratios (up to 25 square meter per kilogram) which points to pieces of foils used in multilayer insulations of spacecraft as possible candidate objects.
During the last years the group was and is deeply involved in various ESA founded feasibility studies for optical observation of artificial space objects vicinity. One study was focusing at the space-based optical observation of small-sized space debris, while other studies helped to define the requirements and to estimate the feasibility, architecture, and performance of a future European Space Surveillance system.
In 2003 the Zimmerwald astrometry facility could be successfully used for the first time to perform a significant number of so-called Near Earth Objects (NEO) follow-up observations. In view of the attention this field of celestial mechanics attracts in the scientific community and in public, the observation of NEOs at Zimmerwald should be viewed as a remarkable success.
