Space Geodesy Branch Highlights, August 2002 CONT02 VLBI Campaign Scientific and technical goals for CONT02: Science: comparison of tidal and atmospheric models with observations particularly at the M2 and S1 frequencies. Technique improvement: troposphere zenith delay and gradients across daily boundaries; use of water vapor radiometers. Accuracy assessment: terrestrial reference frame repeatability day to day. Comparisons: detailed GPS and SLR daily and sub-daily comparisons. VLBI (very long baseline interferometry) is a radio astronomical technique that NASA developed further in the 1970s for Earth science studies. Significant findings from activities like the Crustal Dynamics Project included measurement of contemporary tectonic plate motion and detection of broad deformation zones at plate boundaries. Weekly and more frequent observations are used to measure variations in the Earth’s rotation and orientation, initially with precision of a few cms. Continuous 24/7 observing for a few weeks has been undertaken (e.g., 1994, 1997) to study high frequency phenomena. Such continuous observing requires a special effort from the participating VLBI stations. The International VLBI Service for Geodesy and Astrometry (IVS) set up a 15-day campaign of continuous VLBI observations, named CONT02, to take place October 16-31, 2002. The goal of CONT02 is to acquire state of the art VLBI data over a continuous two-week period to demonstrate the highest accuracy of which VLBI is capable. The campaign is designed to achieve simulated Earth Orientation Parameter results at least as good as 60μarcsec for pole position and 2μsec for UT1.