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History

The Beginning

The observatory was built 1955/1956. In the first three years observations were performed using a small Schmidt Camera (25 cm aperture, 104 cm focal length).

Since 1959 the larger Schmidt Camera (40 cm aperture, 104 cm focal length) as well as a Cassegrain telescope (60 cm aperture, 13 m focal length), both fixed to the same equatorial mount, are at disposal.

Most of the scientific observations were based on the Schmidt camera, which was specially suited for sky surveillance work thanks to the large field of view of 6 degrees.

Photographic Observations

On March 1957 Prof. Max Schürer detected a supernova (magnitude 14) in the galaxy NGC2841.

On October 2, 1957 Prof. Paul Wild detected his first comet 1957f. Worth to mention is the comet Wild-2 detected in 1978. On January 2, 2004 NASA’s stardust spacecraft flew through the comet’s tail, collected and brought back to Earth samples of the tail’s dust.

Upon the initiative of Prof. Schürer the Astronomical Institute has participated in the first global campaigns of optical observations of active and passive geodetic satellites since about 1965: GEOS, Explorer, Pageos and Echo were the most important geodetic targets for the Zimmerwald Schmidt camera. As a result Zimmerwald appeared for the first time in a global network of satellite observatories. The accuracy of the station coordinates determined by these first space-geodetic observations were of the order of 5 meters.

Mid 1970s the photographic observation technique was abandoned. The main reasons were the extremely time-consuming evaluation of the photographic plates and the introduction of a new observation technique: The satellite laser ranging.

Laser Observations

1971-1972: Very preliminary tests with a ruby laser built by the Institute for Applied Physics of the University of Bern (IAP) and mounted along the tube of the astronomical telescope, using the Cassegrain mirror as receiving telescope. Collection of valuable experiences but very limited actual success.

1974-1976: Construction of the satellite observatory Zimmerwald (an annex to the observatory with a new dome) in collaboration with the IAP

1976-1979: First successful ranging with the ruby laser. Accuracy about 80 cm.

1981-1984: Installation of a laser (Neodyme:YAG). Optics, electronic components, software and ranging accuracy (8 cm!) were significantly improved.

1987: Prof. Werner Gurtner becomes head of the Zimmerwald observatory.

The Fundamental Station

Since 1984 the satellite observatory has been operational, taking part in many international observation campaigns, such as

  • MERIT, a project of 14 months (1983/1984) for the determination of the rotation of the Earth using all space techniques available at that time.
  • Wegener Medlas to investigate the geotectonic properties of the Mediterranean area,
  • NASA’s Crustal Dynamics Project (CDP) for global and regional geodynamics,
  • IERS (International Earth Rotation and Reference Systems Service), developed from the MERIT project.

Astrometric observations in Zimmerwald were resumed with the acquisition of a first CCD camera (charge coupled device) in 1989.

In 1990 the station was connected to the internet.

In 1992 the collaboration with the Federal Office of Topography (swisstopo) was significantly intensified. Since this year engineers of swisstopo have participated in the operation of the laser station.

In 1995 the Geodesy and Geodynamics Laboratory of the Federal Institute of Technology (ETH) installed a permanent Earth tide gravimeter at the Zimmerwald observatory.

ZIMLAT, a new 1-meter telescope for astrometric observations and laser ranging was inaugurated in 1997.

The International Laser Ranging Service (ILRS) was founded in 1998. Zimmerwald becomes a tracking station of this service.

2006: Zimmerwald celebrates its 50 years anniversary. The Institute for Applied Physics builds an annex to the station for atmospheric observations. The Astronomical Institute installs a robotic telescope for optical observations of satellites on the roof of the new building.

2009: Prof. Dr. Thomas Schildknecht becomes head of the Zimmerwald observatory.

In that year laser signals were sent successfully to the Lunar Reconnaissance Orbiter (LRO).

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