Scheduling for next era operations of geodetic VLBI : simulations with the AuScope array

The technique of Very Long Baseline Interferometry (VLBI) is an important method for the collection of geodetic and astrometric data. At least two telescopes simultaneously observe signals from a range of extra-galactic radio sources, coordinated by a well-optimised observing schedule. Improving this scheduling process is an important focus as we move into the next generation of geodetic VLBI. This project considered Earth Orientation Parameters (EOPs) and station coordinates, in order to develop our understanding of the capabilities and limitations of the traditional scheduling method, as well as the new, automated scheduling mode 'dynamic scheduling'. Scheduling with the Australian AuScope VLBI array, in particular, was considered through a regime of repeated scheduling, simulation and analysis. However, the findings are widely applicable to other stations and networks hoping to maximise their effective operations in line with the global goals of the geodetic community. We find that short interruptions to a standard 24 hour schedule will not significantly impact the precision of results. This is true even if the total time lost is up to half the total observing time. Conversely, reducing the length of the observing period results in an exponential-like degradation of precision. The dynamic scheduling mode is shown to be capable of producing results consistent with current scheduling. However, it is significantly more flexible, with close to real-time adaptability. It is shown that the baseline-limited AuScope array can also be augmented dynamically to improve EOP precision through an intermittent contribution from only 2 additional global stations. The results presented here confirm that a positive impact on efficiency and precision in geodetic VLBI can be achieved through effective scheduling. In light of this, the current scheduling practice can be adapted immediately for greater operational capability.