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Very Long Baseline Interferometry (VLBI) is an interferometric measuring method, which is used in geodesy as well as in radioastronomy. Spacial separated radiotelescopes observe simultaneously quasars at the edge of the universe (3-13 billons years of light distance). After the observations the interferometer is setup in a computer with the data from all co-observing observatories at one of the correlation centers.

With VLBI one determines the position of the rotational axis and the rotational speed of Earth within 0.2mas (milliarcsecond), intercontinental distances (1.000-12.000km) of the radiotelescopes within a few millimetre as well as the position and Earth rotation parameters, which are necessary for the orientation of global terrestrial reference frames.

The catalog of quasar positions based on VLBI-observations realizes according to one resolution of the International Astronomical Union the primary celestial reference system ICRS. VLBI tells us, where the earth is located in the universe.


TIGO operates a 6m-radiotelescope with a cooled amplifier operating at -252°C for S-band (2.2-2.4GHz) and X-band (8.0-9.0GHz). The data acquisition is performed with the VLB4, Mk5 or the S2 recording system. As frequency normal two hydrogen masers are available (Allan variance 10-15).

In Concepción TIGO performs about 120 observatins series with 24 hour duration each. Usually the observations are requested by the Coordination Center of the International VLBI Service (IVS).