Analysis of Lunar Laser Ranging Data and Performance and Analysis of VLBI Observations for Geodetic Purposes

摘要

Lunar laser ranging (LLR) observations made by the McDonald Observatory from 1970 through 1980 have been analyzed to estimate the variation of latitude and Universal Time (UT). We have compared these estimates with determinations of earth rotation from other techniques. For observations obtained in two one-week periods in September and October 1980, during the International 'MERIT' (Measurement of Earth Rotation and Intercomparison of Techniques) Short Campaign, the root-mean-square difference between LLR and very long baseline interferometry determinations of UT was 0.3 milliseconds. We have also used LLR determinations of UT to derive changes in length-of-day (lod) and compared these with changes in lod inferred from changes in the polar component of the earth's atmospheric angular momentum. A common, persistent approx. 50-day fluctuation was identified in these lod values.