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53-541: LOFAR may refer to: Low-Frequency Array , a large radio telescope system based in the Netherlands Low Frequency Analyzer and Recorder and Low Frequency Analysis and Recording, for low frequency sounds Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title LOFAR . If an internal link led you here, you may wish to change

106-524: A VHF receiver either in stand-alone mode or part of a bistatic radar system together with EISCAT transmitter in Tromsø . Data transport requirements are in the range of several gigabits per second per station and the processing power needed is several tens of TeraFLOPS . The data from LOFAR is stored in the LOFAR long-term archive. The archive is implemented as distributed storage, with data spread over

159-556: A "mini-array" of 19 crossed-dipole antennas, distributed in a circle with a diameter of approximately 400 m. The tiles are a hexagonal cluster with analogically phased antennas. The telescope can capture radio frequencies in the 10–85 MHz range, covering the LOFAR-Low Band (30–80 MHz) range as well. The NenuFAR array can work as a high-sensitivity LOFAR-compatible super-LBA station (LSS), operating together with rest of LOFAR to increase to array's global sensitivity by nearly

212-630: A 110 m long coaxial cable to the receiver unit (RCU). On April 26, 2005, an IBM Blue Gene/L supercomputer was installed at the University of Groningen 's math centre, for LOFAR's data processing . At that time it was the second most powerful supercomputer in Europe , after the MareNostrum in Barcelona . Since 2014 an even more powerful computing cluster (correlator) called COBALT performs

265-568: A GPU-based correlator and beamformer, COBALT, for that task. LOFAR is also a technology and science pathfinder 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

318-574: A Y-shaped array and all the equipment, instrumentation, and computing power to function as an interferometer . Each of the massive telescopes is mounted on double parallel railroad tracks, so the radius and density of the array can be transformed to adjust the balance between its angular resolution and its surface brightness sensitivity. Astronomers using the VLA have made key observations of black holes and protoplanetary disks around young stars , discovered magnetic filaments and traced complex gas motions at

371-542: A deep survey for radio pulsars at low radio frequencies, and will attempt to detect giant radio bursts from rotating neutron stars in distant galaxies. LOFAR offers a unique possibility in particle physics for studying the origin of high-energy and ultra-high-energy cosmic rays (HECRs and UHECRs) at energies between 10 –10 eV. Both the sites and processes for accelerating particles are unknown. Possible candidate sources of these HECRs are shocks in radio lobes of powerful radio galaxies, intergalactic shocks created during

424-493: A factor of two, and improve the array's imaging capabilities. It can also function as a second supercore to improve array availability. Due to its dedicated receiver, NenuFAR can also operate as a standalone instrument, known as NenuFAR/Standalone in this mode. Additionally, a set of LOFAR antennas is deployed at the KAIRA (Kilpisjärvi Atmospheric Imaging Receiver Array) near Kilpisjärvi , Finland . This installation functions as

477-415: A given time plus one spare, each of which has a dish diameter of 25 meters (82 feet) and weighs 209 metric tons (230 short tons ). The antennas are distributed along the three arms of a track, shaped in a wye (or Y) -configuration, (each of which measures 21 kilometres (13 mi) long). Using the rail tracks that follow each of these arms—and that, at one point, intersect with U.S. Route 60 at

530-505: A level crossing—and a specially designed lifting locomotive ("Hein's Trein"), the antennas can be physically relocated to a number of prepared positions, allowing aperture synthesis interferometry with up to 351 independent baselines: in essence, the array acts as a single antenna with a variable diameter. The angular resolution that can be reached is between 0.2 and 0.04 arcseconds . There are four commonly used configurations, designated A (the largest) through D (the tightest, when all

583-481: A modern concept, in which the signals from the separate antennas are not connected directly electrically to act as a single large antenna, as they are in most array antennas . Instead, the LOFAR dipole antennas (of two types) are distributed in stations, within which the antenna signals can be partly combined in analogue electronics, then digitised, then combined again across the full station. This step-wise approach provides great flexibility in setting and rapidly changing

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636-650: A new era in the monitoring of the radio sky. It will be possible to make sensitive radio maps of the entire sky visible from The Netherlands (about 60% of the entire sky) in only one night. Transient radio phenomena, only hinted at by previous narrow-field surveys, will be discovered, rapidly localised with unprecedented accuracy, and automatically compared to data from other facilities (e.g. gamma-ray, optical, and X-ray observatories). Such transient phenomena may be associated with exploding stars, black holes, flares on Sun-like stars, radio bursts from exoplanets or even SETI signals. In addition, this key science project will make

689-594: A new name for the array, and in January 2012 it was announced that the array would be renamed the " Karl G. Jansky Very Large Array". On March 31, 2012, the VLA was officially renamed in a ceremony inside the Antenna Assembly Building. The VLA is a multi-purpose instrument designed to allow investigations of many astronomical objects, including radio galaxies , quasars , pulsars , supernova remnants, gamma-ray bursts , radio-emitting stars ,

742-682: Is 74 MHz to 50 GHz (400 cm to 0.7 cm). The Pete V. Domenici Science Operations Center (DSOC) for the VLA is located on the campus of the New Mexico Institute of Mining and Technology in Socorro, New Mexico . The DSOC also serves as the control center for the Very Long Baseline Array (VLBA), a VLBI array of ten 25-meter dishes located from Hawaii in the west to the U.S. Virgin Islands in

795-483: Is a centimeter-wavelength radio astronomy observatory in the southwestern United States built in the 1970s. It lies in central New Mexico on the Plains of San Agustin , between the towns of Magdalena and Datil , approximately 50 miles (80 km) west of Socorro . The VLA comprises twenty-eight 25-meter radio telescopes (twenty-seven of which are operational while one is always rotating through maintenance) deployed in

848-509: Is planned as soon as upgraded (so-called LOFAR2.0) hardware becomes available. Further stations in other European countries are in various stages of planning. The total effective collecting area is approximately 300,000 square meters, depending on frequency and antenna configuration. Until 2014, data processing was performed by a Blue Gene/P supercomputer situated in the Netherlands at the University of Groningen . Since 2014 LOFAR uses

901-524: Is small, and disentangling it from the much stronger foreground emission is challenging. One of the most important applications of LOFAR will be to carry out large-sky surveys. Such surveys are well suited to the characteristics of LOFAR and have been designated as one of the key projects that have driven LOFAR since its inception. Such deep LOFAR surveys of the accessible sky at several frequencies will provide unique catalogues of radio sources for investigating several fundamental areas of astrophysics, including

954-476: Is thought that the 'Dark Ages', the period after recombination when the Universe turned neutral, lasted until around z=20. WMAP polarization results appear to suggest that there may have been extended, or even multiple phases of reionisation, the start possibly being around z~15–20 and ending at z~6. Using LOFAR, the redshift range from z=11.4 (115 MHz) to z=6 (200 MHz) can be probed. The expected signal

1007-740: The Milky Way 's center, probed the Universe's cosmological parameters, and provided new knowledge about the physical mechanisms that produce radio emission . The VLA stands at an elevation of 6,970 feet (2,120 m) above sea level. It is a component of the National Radio Astronomy Observatory (NRAO). The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc . The radio telescope comprises 27 independent antennas in use at

1060-656: The NRAO VLA Sky Survey and Faint Images of the Radio Sky at Twenty-Centimeters . In September 2017 the VLA Sky Survey (VLASS) began. This survey will cover the entire sky visible to the VLA (80% of the Earth's sky) in three full scans. Astronomers expect to find about 10 million new objects with the survey — four times more than what is presently known. The driving force for the development of

1113-438: The National Radio Astronomy Observatory announced that they will be replacing the ageing antennae with 160 new ones at the site, plus 100 auxiliary antennae located across North America. The project, estimated to cost about $ 2 billion to build and around $ 90 million to run, will vastly expand the capabilities of the current installation and increase the frequency sensitivity from 50 GHz to over 100 GHz. The facility will be renamed

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1166-762: The Solar Dynamics Observatory (SDO) , and eventually the Advanced Technology Solar Telescope and the Solar Orbiter provide insights into this fundamental astrophysical process. In the early 1990s, the study of aperture array technology for radio astronomy was being actively studied by ASTRON – the Netherlands Institute for Radio Astronomy. At the same time, scientific interest in a low-frequency radio telescope began to emerge at ASTRON and at

1219-740: The Target data centre located in the Donald Smits Center for Information Technology at the University of Groningen , SURFsara  [ nl ] centre in Amsterdam, and the Forschungszentrum Jülich in Germany. The mission of LOFAR is to map the Universe at radio frequencies from ~10–240 MHz with greater resolution and greater sensitivity than previous surveys, such as the 7C and 8C surveys, and surveys by

1272-588: The Very Large Array (VLA) and Giant Meterwave Radio Telescope (GMRT) . LOFAR will be the most sensitive radio observatory at its low observing frequencies until the Square Kilometre Array (SKA) comes online in the late 2020s. Even then, the SKA will only observe at frequencies >50 MHz and LOFAR's angular resolution will remain far superior. The sensitivities and spatial resolutions attainable with LOFAR make possible several fundamental new studies of

1325-542: 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 ). LOFAR combines aspects of many of these earlier telescopes; in particular, it uses omnidirectional dipole antennas as elements of a phased array at individual stations, and combines those phased arrays using

1378-411: The aperture synthesis technique developed in the 1950s. Like the earlier Cambridge Low Frequency Synthesis Telescope (CLFST) low-frequency radio telescope, the design of LOFAR has concentrated on the use of large numbers of relatively cheap antennas without any moving parts, concentrated in stations, with the mapping performed using aperture synthesis software . The direction of observation ("beam") of

1431-692: The sun and planets , astrophysical masers , black holes , and the hydrogen gas that constitutes a large portion of the Milky Way galaxy as well as external galaxies. In 1989 the VLA was used to receive radio communications from the Voyager 2 spacecraft as it flew by Neptune . A search of the galaxies M31 and M32 was conducted in December 2014 through January 2015 with the intent of quickly searching trillions of systems for extremely powerful signals from advanced civilizations. It has been used to carry out several large surveys of radio sources, including

1484-410: The " Next Generation Very Large Array ". The VLA is located between the towns of Magdalena and Datil , about 50 miles (80 km) west of Socorro, New Mexico . U.S. Route 60 passes east–west through the complex. The VLA site is open to visitors with paid admission. A visitor center houses a small museum, theater, and a gift shop. A self-guided walking tour is available, as the visitor center

1537-786: The Dutch Universities. A feasibility study was carried out and international partners sought during 1999. In 2000 the Netherlands LOFAR Steering Committee was set up by the ASTRON Board with representatives from all interested Dutch university departments and ASTRON. In November 2003 the Dutch Government allocated 52 million euro to fund the infrastructure of LOFAR under the Bsik programme. In accordance with Bsik guidelines, LOFAR

1590-586: The LOFAR array. To make radio surveys of the sky with adequate resolution, the antennas are arranged in clusters that are spread out over an area of more than 1000 km in diameter. The LOFAR stations in the Netherlands reach baselines of about 100 km. LOFAR currently receives data from 24 core stations (in Exloo ), 14 'remote' stations in The Netherlands, and 14 international stations. Each of

1643-441: The LOFAR stations are digitised, transported to a central digital processor, and combined in software in order to map the sky. Therefore, LOFAR is a "software telescope". The cost of such telescopes is dominated by the cost of electronics and will therefore mostly follow Moore's law , becoming cheaper with time and allowing increasingly large telescopes to be built. Each antenna is fairly simple- but there are about 20,000 of them in

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1696-748: The Netherlands, built with regional and national funding. The six stations in Germany , three in Poland , and one each in France , Great Britain , Ireland , Latvia , and Sweden , with various national, regional, and local funding and ownership. Italy officially joined the International LOFAR Telescope (ILT) in 2018; construction at the INAF observatory site in Medicina , near Bologna ,

1749-460: The Universe as well as facilitating unique practical investigations of the Earth's environment. In the following list the term z is a dimensionless quantity indicating the redshift of the radio sources seen by LOFAR. One of the most exciting, but technically most challenging, applications of LOFAR will be the search for redshifted 21 cm line emission from the Epoch of Reionization (EoR). It

1802-588: The VLA was David S. Heeschen . He is noted as having "sustained and guided the development of the best radio astronomy observatory in the world for sixteen years." Congressional approval for the VLA project was given in August 1972, and construction began some six months later. The first antenna was put into place in September 1975 and the complex was formally inaugurated in 1980, after a total investment of US$ 78,500,000 (equivalent to $ 290,000,000 in 2023). It

1855-469: The central cluster with 48 dipoles and other three clusters with 16 dipoles each. Each cluster is about 100 m in size. The clusters are distributed over an area of ~500 m in diameter. In November 2007 the first international LOFAR station ( DE601 ) next to the Effelsberg 100 m radio telescope became the first operational station. The first fully complete station, ( CS302 ) on the edge of the LOFAR core,

1908-546: The core and remote stations has 48 HBAs and 96 LBAs and a total of 48 digital Receiver Units (RCUs). International stations have 96 LBAs and 96 HBAs and a total of 96 digital Receiver Units (RCUs). The locations of the international LOFAR stations are: The NenuFAR telescope is co-located at the Nançay radio telescope . It is an extension of the Nançay LOFAR station (FR606), adding 96 low frequency tiles, each consisting of

1961-408: The correlation of signals from all individual stations. In August/September 2006 the first LOFAR station ( Core Station CS001 , aka. CS1 52°54′32″N 6°52′8″E  /  52.90889°N 6.86889°E  / 52.90889; 6.86889 ) was put in the field using pre-production hardware. A total of 96 dual-dipole antennas (the equivalent of a full LOFAR station) are grouped in four clusters,

2014-490: The directional sensitivity on the sky of an antenna station. The data from all stations are then transported over fiber to a central digital processor, and combined in software to emulate a conventional radio telescope dish with a resolving power corresponding to the greatest distance between the antenna stations across Europe. LOFAR is thus an interferometric array, using about 20,000 small antennas concentrated in 52 stations since 2019. 38 of these stations are distributed across

2067-501: The dishes are within 600 metres (2,000 ft) of the center point). The observatory normally cycles through all the various possible configurations (including several hybrids) every 16 months; the antennas are moved every three to four months. Moves to smaller configurations are done in two stages, first shortening the east and west arms and later shortening the north arm. This allows for a short period of improved imaging of extremely northerly or southerly sources. The frequency coverage

2120-422: The east that constitutes the world's largest dedicated, full-time astronomical instrument. In 2011, a decade-long upgrade project resulted in the VLA expanding its technical capacities by factors of up to 8,000. The 1970s-era electronics were replaced with state-of-the-art equipment. To reflect this increased capacity, VLA officials asked for input from both the scientific community and the public in coming up with

2173-400: The epoch of galaxy formation, so-called Hyper-novae, gamma-ray bursts , or decay products of super-massive particles from topological defects, left over from phase transitions in the early Universe. The primary observable is the intense radio pulse that is produced when a primary CR hits the atmosphere and produces an extensive air shower (EAS). An EAS is aligned along the direction of motion of

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2226-473: The first to detect weak radio emission from such regions. LOFAR will also measure the Faraday effect , which is the rotation of polarization plane of low-frequency radio waves, and gives another tool to detect weak magnetic fields. The Sun is an intense radio source. The already strong thermal radiation of the 10 K hot solar corona is superimposed by intense radio bursts that are associated with phenomena of

2279-594: The flight (N60NA) experienced an uncontained engine failure , causing cabin decompression . In 1997 the VLA featured in Contact , the film adaptation of the book by the same name written by Carl Sagan . With a view to upgrading the venerable 1970s technology with which the VLA was built, the VLA has evolved into the Expanded Very Large Array (EVLA). The upgrade has enhanced the instrument's sensitivity, frequency range, and resolution with

2332-649: The formation of massive black holes , galaxies and clusters of galaxies. Because the LOFAR surveys will probe an unexplored parameter of the Universe, it is likely that they will discover new phenomena. In February 2021, astronomers released, for the first time, a very high-resolution image of 25,000 active supermassive black holes , covering four percent of the Northern celestial hemisphere , based on ultra-low radio wavelengths , as detected by LOFAR. The combination of low frequencies, omnidirectional antennae, high-speed data transport and computing means that LOFAR will open

2385-505: The installation of new hardware at the San Agustin site. A second phase of this upgrade may add up to eight additional antennae in other parts of the state of New Mexico , up to 190 miles (300 km) away, if funded. Magdalena Ridge Observatory is a new observatory a few miles south of the VLA, and is run by VLA collaborator New Mexico Tech . Under construction at this site is a ten-element optical interferometer . In June 2023,

2438-437: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=LOFAR&oldid=1190094479 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Low-Frequency Array LOFAR consists of a vast array of omnidirectional radio antennas using

2491-499: The primary particle, and a substantial part of its component consists of electron-positron pairs which emit radio emission in the terrestrial magnetosphere (e.g., geo-synchrotron emission). LOFAR opens the window to the so far unexplored low-energy synchrotron radio waves, emitted by cosmic-ray electrons in weak magnetic fields. Very little is known about the origin and evolution of cosmic magnetic fields. The space around galaxies and between galaxies may all be magnetic, and LOFAR may be

2544-434: The solar activity as the root of space weather. Furthermore, LOFAR's flexibility enables rapid responses to solar radio bursts with follow-up observations. Solar flares produce energetic electrons that not only lead to the emission of non-thermal solar radio radiation. The electrons also emit X-rays and heat the ambient plasma. So joint observation campaigns with other ground- and space-based instruments, e.g. RHESSI , Hinode ,

2597-502: The solar activity, like flares and coronal mass ejections (CMEs). Solar radio radiation in the LOFAR frequency range is emitted in the middle and upper corona. So LOFAR is an ideal instrument for studies of the launch of CMEs heading towards interplanetary space. LOFAR's imaging capabilities will yield information on whether such a CMEs might hit the Earth. This makes LOFAR is a valuable instrument for space weather studies. Solar observations with LOFAR will include routine monitoring of

2650-489: The stations is chosen electronically by phase delays between the antennas. LOFAR can observe in several directions simultaneously, as long as the aggregated data rate remains under its cap. This in principle allows a multi-user operation. LOFAR makes observations in the 10 MHz to 240 MHz frequency range with two types of antennas: Low Band Antenna (LBA) and High Band Antenna (HBA), optimized for 10–80 MHz and 120–240 MHz respectively. The electric signals from

2703-737: Was delivered in May 2009, with a total of 40 Dutch stations scheduled for completion in 2013. By 2014, 38 stations in the Netherlands, five stations in Germany (Effelsberg, Tautenburg, Unterweilenbach, Bornim/Potsdam, and Jülich), and one each in the UK (Chilbolton), in France (Nançay) and in Sweden (Onsala) were operational. LOFAR was officially opened on 12 June 2010 by Queen Beatrix of the Netherlands. Regular observations started in December 2012. Very Large Array The Karl G. Jansky Very Large Array ( VLA )

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2756-422: Was funded as a multidisciplinary sensor array to facilitate research in geophysics , computer sciences and agriculture as well as astronomy . In December 2003 LOFAR's Initial Test Station (ITS) became operational. The ITS system consists of 60 inverse V-shaped dipoles; each dipole is connected to a low-noise amplifier (LNA), which provides enough amplification of the incoming signals to transport them over

2809-470: Was the largest configuration of radio telescopes in the world. During construction in 1975, workers laying the tracks for the northern arm of the array discovered a human skeleton north of US-60 . A year later, the remains were identified as belonging to a male airline passenger who was ejected from National Airlines Flight 27 at 39,000 feet (12,000 m) two years earlier, after the DC-10-10 servicing

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