IAU Colloquium 63 was held in Grasse, France, May 22–27, 1981. The colloquium was sponsored by the International Astronomical Union (IAU) and cosponsored by the Council of Scientific Unions, Committee on Space Research (COSPAR), and the International Association of Geodesy. The 51 participants at the conference were drawn from a wide geographical region and consisted of observers, responsible for collecting the data; analysts, who apply the data to determine polar motion and earth rotation; and theoreticians, who interpret the results and provide predictions to guide future observation efforts.
The colloquium occurred at a particularly opportune time, since the short MERIT (Monitor Earth Rotation and Intercompare the Techniques of Observation and Analysis) campaign, conducted during August, September, and October 1980, provided a focus for both observation and analysis of efforts to obtain polar motion solutions. Independent solutions were provided by using data from the general categories: laser ranging (Lageos, Starlette and lunar), VLBI (Very Long Baseline Interferometry), satellite Doppler, astrometric (classical methods), and connected element interferometer.