Hana Spicakova

The New Vienna VLBI Software VieVS

New VLBI (Very Long Baseline Interferometry) data analysis software (called Vienna VLBI Software, VieVS) is being developed at the Institute of Geodesy and Geophysics in Vienna taking into consideration all present and future VLBI2010 requirements. The programming language MATLAB is used, which considerably eases the programming efforts because of many built-in functions and tools. MATLAB is the high-end programming language of the students at the Vienna University of Technology and at many other institutes worldwide. VieVS is equipped with the most recent models recommended by the IERS Conventions. The parameterization with piece-wise linear offsets at integer hours in the least-squares adjustment provides flexibility for the combination with other space geodetic techniques. First comparisons with other VLBI software packages show a very good agreement, and there are plans to add further features to VieVS, e.g. capabilities for Kalman filtering, phase delay solutions, and spacecraft tracking.

Systematic Errors of a VLBI Determined TRF Investigated by Simulations

In this study, we investigate the influence of different analysis setup options for the processing of VLBI measurement data from 2002 until 2010 to derive the terrestrial reference frame (TRF). For estimating the consequent changes of the TRF, the simulation tool of the Vienna VLBI Software (VieVS) is used by applying different a priori models. We show that neglecting atmosphere loading causes a systematic annual scale variation of±0.3 mm, and that the application of the cubic model recommended in the most recent IERS Conventions for the mean pole introduces a scale change of −0.6mm over 8.5years. The effects of antenna thermal deformation on the TRF are±0.5 to 1mm/year in translation and±2 mm/year in scale. No systematic effects are found for the different troposphere mapping functions tested. Besides systematic, annual, and episodic impacts on the coordinates, we focus on possible changes in the scale of the reference frames.