Very-long-baseline Interferometry - VLBI Arrays

VLBI Arrays

There are several VLBI arrays located in Europe, Canada, the United States, Russia, Japan and Australia. The most sensitive VLBI array in the world is the European VLBI Network (EVN). This is a part-time array with the data being processed at the Joint Institute for VLBI in Europe (JIVE). The Very Long Baseline Array (VLBA) uses ten dedicated, 25-meter telescopes spanning 5351 miles across the United States, and is the largest VLBI array that operates all year round as both an astronomical and geodesy instrument. The combination of the EVN and VLBA is known as Global VLBI. When one or both of these arrays are combined with one or more space-based VLBI antennas such as HALCA (previously) and now with RadioAstron (Spektr-R), the resolution obtained is higher than any other astronomical instrument, capable of imaging the sky with a level of detail measured in microarcseconds. A notable early example of international cooperation was in 1976, when radio telescopes in the United States, USSR and Australia were linked to observe hydroxyl-maser sources.