Towards fully automated processing of VLBI sessions - results from ultra-rapid UT1 experiments

Like other space geodetic techniques, data processing and analysis of VLBI data requires some human interactions before the target parameters are available to the scientific community. If the processing chain can be completely automated, results would be available independent from time-zones, holidays or illness of the analyst. In VLBI, a lot of effort is put into near real-time monitoring of Earth orientation parameters, especially UT1. Since VLBI is the only space-geodetic technique which gives direct access to the Earth's phase of rotation, i.e. universal time UT1, a low latency product is desirable. Beside multi-baseline sessions, regular single-baseline VLBI experiments are scheduled in order to provide estimates of UT1 for the international science community. Although the turn-around time of such sessions is usually much shorter and results are available within one day after the data were recorded, lower latency of UT1 results is still requested. Based on the experience gained over the last three years, an automated processing chain was established. In July 2010, we started to provide automatically processed results to IERS rapid service, and thus fully unattended operation and robust estimation of UT1 has become routine operation. A new analysis software ensures that all post-processing stages run smoothly and a variety of scripts guarantee that the data-flow to and through the correlator takes full advantage of the available resources. The concept of ultra-rapid VLBI sessions can be extended further to include additional, geometrical well distributed stations, in order to derive also polar motion components with the same latency as UT1 and to provide an up-to-date complete set of Earth orientation parameters for navigation of space and satellite missions. Moreover, our work demonstrates how future VLBI networks can be processed automatically in order to provide near real-time information about the instantaneous Earth orientation in the framework of GGOS.