An Overview of The LBA

Very Long Baseline Interferometry involves a network of telescopes in Australia and overseas. Until 1997, this network had been supported by the individual institutions operating each telescope via a cooperative arrangement.

Under the 1997 Major National Research Facilities program the VLBI network was upgraded and agreement was reached between ATNF and the University of Tasmania to operate the network as a National Facility.

From 2006 the University of Tasmania telescopes at Hobart and Ceduna have been operated under a service agreement between UTas and ATNF.

The National Facility part of this network is the Australian Long Baseline Array (LBA), run by the VLBI Group and collaborators at the ATNF and participating institutions. The Long Baseline Array (LBA) utilises the ATNF telescopes (Parkes, ATCA and Mopra), and the Hobart and Ceduna antennas operated by the University of Tasmania to observe in VLBI mode. Other telescopes may be also requested for special observations. Note that the Tidbinbilla 70-m antenna may be available only for short periods. From 2010 OCT there may be some availability of the Warkworth 12m telescope operated by the Auckland University of Technology at 20, 13 and 3cm, and a single ASKAP antenna with a single pixel feed at 20cm. These new facilities are offered on a best-efforts basis and to observations for which their use significantly adds to the likely science outcomes. Specific system availability may be dependent on availability at individual antennas: the ASKAP antenna, in particular, will only be available if its use does not impact on construction and test work on the ASKAP site.

Unlike The Australia Telescope Compact Array, where the data from each antenna is correlated as it is collected, VLBI is carried out by observing at various telescopes in the network relatively independently of each other. The raw data is transported to a correlator facility and correlated there in real time. Since 2008, the main VLBI correlation for the LBA is done at the Curtin University of Technology using the DiFX software correlator, under a service agreement with ATNF.

This VLBI array is also part of the APT (Australia Pacific Telescope) and VSOP (Space VLBI). The LBA telescopes have been used extensively for VSOP observations.

To carry out VLBI observations with the LBA, proposals must be submitted to the ATNF in the same way as proposals to use other telescopes run by the ATNF.

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