The Australia Telescope Compact Array (ATCA), at the Paul Wild Observatory, is an array of six 22-m antennas used for radio astronomy. It is located about 25 km west of the town of Narrabri in rural NSW (about 500 km north-west of Sydney). It is operated by CSIRO's Astronomy and Space Science division, as are the Parkes Observatory and the Mopra Observatory near Coonabarabran. A fourth radio telescope, the Australian Square Kilometre Array Pathfinder, is also being developed by CSIRO at the Murchison Radio-astronomy Observatory in the Mid-West of Western Australia. Collectively, CSIRO's radio astronomy observatories are known as the Australia Telescope National Facility, with the facility supporting Australia's research in radio astronomy.