The AUSTRAL VLBI observing program

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.