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NASA Goddard Geophysical and Astronomical Observatory

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Current Activities at GGAO

GGAO is one of the few locations in the world where four or more space geodesy techniques are co-located, thus providing scientists a unique opportunity to assess system performance and perform multi-technique analysis. Furthermore, co-located techniques are an integral part to the maintenance of the International Terrestrial Reference Frame (ITRF), is a set of points with their 3-dimensional cartesian coordinates which realize an ideal reference system. Co-location of systems in near proximity also enable (according to the ITRF Web site):

  • calibration of mobile systems using simultaneous measurements of instruments of the same technique
  • repeated measurements on a marker with mobile systems using non-simultaneous measurements of instruments of the same technique
  • changes in antenna location for GPS or DORIS
  • co-locations between instruments of different techniques, which implies eccentricities, except in the case of successive occupancies of a given marker by various mobile systems

The instruments from the four space geodesy techniques co-located at GGAO are:

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