LOFAR
The LOFAR core ("superterp") near Exloo, Netherlands.
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| Location(s) | 3 km north of Exloo, the Netherlands (core) |
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| Coordinates | 52°54′32″N 6°52′08″E / 52.90889°N 6.86889°ECoordinates: 52°54′32″N 6°52′08″E / 52.90889°N 6.86889°E |
| Organisation | ASTRON |
| Wavelength | 30 to 1.3 m (radio) |
| Built | 2006–2012 |
| Telescope style | phased array of about 20,000 dipole antennas |
| Diameter | 1000 km or more |
| Collecting area | up to 1 km2 |
| Focal length | N/A |
| Mounting | fixed |
| Website | www |
 Location of LOFAR in Netherlands.
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The Low-Frequency Array or LOFAR, is a large radio telescope located mainly in the Netherlands, completed in 2012 by ASTRON, the Netherlands Institute for Radio Astronomy and its international partners, and operated by ASTRON's radio observatory, of the Netherlands Organisation for Scientific Research.
LOFAR consists of a vast array of omnidirectional antennas using a new concept in which the signals from the separate antennas are not combined in real time as they are in most array antennas. The electronic signals from the antennas are digitized, transported to a central digital processor, and combined in software to emulate a conventional antenna. The project is based on an interferometric array of radio telescopes using about 20,000 small antennas concentrated in at least 48 stations. Forty of these stations are distributed across the Netherlands and were funded by ASTRON. The five stations in Germany, and one each in Great Britain, France and Sweden, were funded by these countries. Further stations may also be built in other European countries. The total effective collecting area is approximately 300,000 square meters, depending on frequency and antenna configuration. The data processing is performed by a Blue Gene/P supercomputer situated in the Netherlands at the University of Groningen. LOFAR is also a technology precursor for the Square Kilometre Array.
LOFAR was conceived as an innovative effort to force a breakthrough in sensitivity for astronomical observations at radio-frequencies below 250 MHz. Astronomical radio interferometers usually consist either of arrays of parabolic dishes (e.g. the One-Mile Telescope or the Very Large Array), arrays of one-dimensional antennas (e.g. the Molonglo Observatory Synthesis Telescope) or two-dimensional arrays of omnidirectional antennas (e.g. Antony Hewish's Interplanetary Scintillation Array).
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