The contributions of the Zentralinstitut fuer Physik der Erde to the MERIT project

Observations and analyses undertaken as part of the preliminary short campaign of the project to monitor earth-rotation and intercompare the techniques of observation and analysis (MERIT) from August 1 to October 31, 1980, are reported. Optical-observation data for classical determinations of rotation parameters, obtained with two photographic zenith telescopes and a Danjon astrolabe, reveal that the newer telescope gives results comparable in precision to those of other stations. LAGEOS laser range measurements from all stations are analyzed using the POTSDAM-4 orbit-correction program, which takes into account the gravitational field of the earth (up to degree and order 21 of the spherical-function representation), the gravitational forces of the sun and moon, earth tides, the radiation pressure of the sun, and atmospheric friction effects. The results are compared to the BIH astronomical values and to those calculated by other centers and found to be near the overall average.