Optimum design of geodetic VLBI networks and observing strategies (VLBI 2010)
Geodetic VLBI (Very Long Baseline Interferometry) is the principle technique for determining small variations of the spin rate of the Earth, parameters for precession and nutation, and the Celestial Reference Frame realized by the coordinates of extragalactic radio sources. With ever increasing demands on the accuracy, reliability and temporal resolution of these parameters the International VLBI Service for Geodesy and Astrometry (IVS) has to contemplate the optimum design of its networks and observing strategies. Therefore, thorough and systematic simulation studies strongly encouraged by the IVS will be carried out within the project. The investigations will comprise various tasks and options, e.g. observing with multiple antennas at one geodetic VLBI station using the same clock (allowing more than one observation at a time or shorter integration times), the application of one 'global' antenna type for all sites, the selection of optimum locations for new radio telescopes to improve the global coverage with VLBI stations, or the question of the cutoff elevation angle. The project will deliver exact numerical results for the accuracies and correlations between the parameters achieved with certain network designs and observing strategies. Since many accuracy assessments presently used to project VLBI onto 2010 are based on pure assumptions, this project is very important for the IVS to find the optimum setup of future geodetic VLBI systems. The simulation studies are based on three programs: the scheduling software SKED, the VLBI software package OCCAM, and a new software VV-SIM (Vienna VLBI-Simulations) which will be freely available. VV-SIM will take the schedules from SKED to e.g. create sky-plots with regard to certain time intervals, and it will process SINEX (Software Indenpendent Exchange) files from OCCAM to interpret and illustrate the results (e.g. formal errors of the parameters or the correlations between them). Besides providing feedback to the IVS regularily, all the experience gathered in the project will be used to schedule a continuous global VLBI campaign planned by the IVS for 2008 (CONT08).
- Andrea Pany
- Fonds zur Förderung der wissenschaftlichen Forschung (FWF)