Abstract
The AUSTRAL observing program was started in 2011, performing geodetic and astrometric very long baseline interferometry (VLBI) sessions using the new Australian AuScope VLBI antennas at Hobart, Katherine, and Yarragadee, with contribution from the Warkworth (New Zealand) 12 m and Hartebeesthoek (South Africa) 15 m antennas to make a southern hemisphere array of telescopes with similar design and capability. Designed in the style of the next-generation VLBI system, these small and fast antennas allow for a new way of observing, comprising higher data rates and more observations than the standard observing sessions coordinated by the International VLBI Service for Geodesy and Astrometry (IVS). In this contribution, the continuous development of the AUSTRAL sessions is described, leading to an improvement of the results in terms of baseline length repeatabilities by a factor of two since the start of this program. The focus is on the scheduling strategy and increased number of observations, aspects of automated operation, and data logistics, as well as results of the 151 AUSTRAL sessions performed so far. The high number of the AUSTRAL sessions makes them an important contributor to VLBI end-products, such as the terrestrial and celestial reference frames and Earth orientation parameters. We compare AUSTRAL results with other IVS sessions and discuss their suitability for the determination of baselines, station coordinates, source coordinates, and Earth orientation parameters.
Highlights
very long baseline interferometry (VLBI) performance for geodesy and astrometry relies on a global network of antennas that are compatible in sensitivity, frequency coverage, and slew speed
We have presented some general statistics of these observations and described how a high cadence observing program paired with targeted research enabled a significant improvement in the number of observations and results
We find that a comprehensive understanding of all aspects of the observations, which was achieved in the course of this program, was essential for this
Summary
VLBI performance for geodesy and astrometry relies on a global network of antennas that are compatible in sensitivity, frequency coverage, and slew speed. The main attributes of VGOS are a much greater number of observations, both in total and per time unit This shall be enabled by faster antenna slew speeds and shorter on-source times, with the ultimate goal of continuous (24/7) observations. The AuScope VLBI array is dedicated to geodetic and astrometric observations and designed for future VGOS compatibility At present, it is equipped with legacy S/X receivers and state-of-the-art back-end and recording systems (Lovell et al 2013). Since the first AUSTRAL session, this observing program has been the subject to continuous improvements, predominantly as a result of careful optimisation in the scheduling.
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