Canadian Geodetic Long Baseline Interferometry

The Canadian Geodetic Long Baseline Interferometry (CGLBI) research is Canada's representative to the International VLBI Service for Geodesy and Astrometry.  The research activities of the CGLBI team are presented here.

Modern Geodesy relies on astronomical and space-based techniques, namely Very Long Baseline Interferometry (VLBI), GPS (the Global Positioning System), SLR (Satellite Laser Ranging) and LLR (Lunar Laser Ranging).

IAG commission VIII (International Coordination of Space Techniques for Geodesy and Geodynamics (CSTG)) discusses the different space techniques in its status report for 1996, and argues that "Only VLBI is capable of defining the Celestial Reference Frame, which serves as the inertial system in satellite geodesy. Long-term stability of UT1-UTC and of precession/nutation can only be guaranteed by this technique." Their summary states: "It is clear from the scientific point of view that VLBI, Laser Ranging (SLR and LLR), and satellite microwave techniques are indispensable as contributors to space geodesy."

The Canadian contribution to Geodetic VLBI is substantial. The Algonquin Radio Observatory is a leading site for Geodetic VLBI with a very long history of observations. Continued operation of the Yellowknife antenna is important for studies of the North American Plate. The Canadian- developed S2 VLBI system is a complete system consisting of recording terminals, data acquisition systems, playback terminals and a correlator.

The CGLBI partners operate the Algonquin and Yellowknife observatories as part of global networks within the International VLBI Service for Geodesy and Astrometry.  The Algonquin observatory is the most sensitive regularly participating antenna in Geodetic VLBI.

The CGLBI research consists of three Canadian GPS observatories supplied with S2 equipment, the S2 Correlator and associated operational capabilities. Following the development and testing stage, the research activities will involve moving the transportable antenna to the CACS locations and making an extensive series of VLBI measurements to determine the site positions in the International Terrestrial Reference Frame (ITRF). This information will be used to strengthen the geometry of the ACS network and global reference frames. 

Following the implementation of S2 GPS equipment in Canada, it is expected that cooperation in international geodetic GPS observing studies using this technology will take place.