A local geodetic network is needed for the tie of the reference points of the individual geodetic space techniques VLBI, SLR and GNSS. The local survey relates the intersection of the axes of the telescopes and the center of the GNSS antennas to each other.
The resulting space vectors between the reference points of VLBI, SLR, GNSS allow the transformation of the individual space technique dependent global reference frames to the most accurate International Terrestrial Reference Frame (ITRF).
The Geodetic Observatory TIGO is a fundamental station for geodesy which provides the geometric tie of the geodetic space techniques VLBI, SLR, GNSS and gravimetry by the local geodetic network. The local geodetic network was first time measured in 2003.
A regional network of permanent GPS-stations complements the local survey. The installation was finished in 2008. It serves for the monitoring of the regional tectonics in a subduction zone, in which TIGO was installed.
This regional network consists of four additional permanent GPS stations which had been distributed in about 15-70km distance in four opposite directions around TIGO. The stations are located in Dichato, Faro Hualpen, Santa Juana and Bulnes.
The station Dichato is located directly at the Pacific Ocean and collocated with a tide gauge. The tide gauge was tied with a precision levelling to the local network of TIGO. This is important for the definition of vertical reference systems with TIGO. It is intended also to perform a long-term monitoring of the mean sea level.