Thursday, August 4, 2011

NGS Conducts Geodetic Techniques Site Survey

The National Geodetic Survey, in support of the International Earth Rotation & Reference Systems Service (IERS), is finalizing a geodetic site survey this week at the National Radio Astronomy Observatory in Brewster, Washington. The survey will very precisely measure the local tie vector (direction and distance) between two geodetic antennae co-located on site: Very Long Baseline Interferometry and the Global Positioning System. A primary objective of the IERS is to serve the astronomical, geodetic, and geophysical communities by providing realizations of the International Terrestrial Reference Frame—the global coordinate system used for most scientific analysis, including measuring sea level change. To be truly meaningful to the IERS, local tie vector information must be determined at the highest achievable level of accuracy through a site survey (preferably at the 1 millimeter level). Without such surveys, the global coordinate frame for measuring sea level change would not be accurate enough to detect annual signals of 1-2 mm per year. For more information, contact Kendall Fancher.