MeerKAT, originally the Karoo Array Telescope, is a radio telescope consisting of 64 antennas in the Meerkat National Park, in the Northern Cape of South Africa. In 2003, South Africa submitted an expression of interest to host the Square Kilometre Array (SKA) Radio Telescope in Africa, and the locally designed and built MeerKAT was incorporated into the first phase of the SKA. MeerKAT was launched in 2018.
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MeerKAT is a precursor for the SKA-mid array, as are the Hydrogen Epoch of Reionization Array (HERA), the Australian SKA Pathfinder (ASKAP) and the Murchison Widefield Array (MWA).[1]
Description
It is located on the SKA site in the Karoo, and is a pathfinder for SKA-mid technologies and science. It was designed by engineers within the South Africa Radio Astronomy Observatory and South African industries, and most of the hardware and software was sourced in South Africa. It comprises 64 antennas, each 13.5m in diameter, equipped with cryogenic receivers. The antennas have positions for four receivers, and one of the three vacant positions will be filled by S-band receivers provided by the Max Planck Institute for Radio Astronomy (MPIfR). The array configuration has 61% of the antennas located within a 1km diameter circle, and the remaining 39% distributed out to a radius of 4km.[citation needed]
The receiver outputs are digitised immediately at the antenna, and the digital data streams are transported to the Karoo Array Processor Building (KAPB) via buried optical fibres. The antenna signals are processed by the Correlator/Beamformer (CBF) digital signal processor. Data from the CBF is passed on to the Science Processor computer cluster and disk storage modules. The MeerKAT antenna data is also made available to a number of user-supplied digital backends via the CBF, including pulsar and fast radio burst (FRB) search engines, a precision pulsar timing system, and a SETI signal processor. A time and frequency reference (TFR) system provides clock and absolute time signals required by the digitisers and other telescope subsystems. This TFR system comprises two hydrogen maser clocks, two rubidium atomic clocks, a precise crystal oscillator, and a set of GNSS receiver systems for time transfer with UTC.[citation needed]
The massive computing and digital signal-processing systems located at the KAPB are housed in a large shielded chamber (or Faraday cage) to prevent radio signals from the equipment interfering with the sensitive radio receivers. The KAPB itself is partially buried below ground level to provide additional radio frequency interference (RFI) protection, and to provide temperature stability. The KAPB also houses a power conditioning facility for the entire site, including three diesel rotary UPS units that provide an uninterrupted power supply to the whole site.[2]
A long-haul optical fibre transfers data from the KAPB to the Centre for High Performance Computing (CHPC) and SARAO office in Cape Town, and provides a control and monitoring link to the SARAO operations centre in Cape Town. Telescope data processing and reduction is executed on compute facilities provided by the MeerKAT SP systems, and on other high performance computer facilities provides by MeerKAT users.[citation needed]
Specifications
MeerKAT inaugurated in July 2018[3] consists of 64 dishes of 13.5 metres in diameter each with an offset Gregorian configuration.[4] An offset dish configuration has been chosen because its unblocked aperture provides uncompromised optical performance and sensitivity, excellent imaging quality and good rejection of unwanted radio frequency interference from satellites and terrestrial transmitters. It also facilitates the installation of multiple receiver systems in the primary and secondary focal areas and is the reference design for the mid-band SKA concept.[5]
MeerKAT supports a wide range of observing modes, including deep continuum, polarisation and spectral line imaging, pulsar timing and transient searches. A range of standard data products are provided, including an imaging pipeline. A number of "data spigots" are also available to support user-provided instrumentation. Significant design and qualification efforts are planned to ensure high reliability to achieve low operational cost and high availability.
Specifications
Number of antennae
64
Dish diameter
13.5 m
Minimum baseline
29 m
Maximum baseline
8km
Frequency bands (receivers)
0.58 – 1.015GHz 0.9 - 1.67GHz 8 – 14.5GHz
Continuum imaging dynamic range at 1.4GHz
60dB
Line-to-line dynamic range at 1.4GHz
40dB
Mosaicing imaging dynamic range at 1.4GHz
27dB
Linear polarisation cross coupling across −3dB beam
−30dB
MeerKAT's 64 dishes are distributed over two components:
A dense inner component containing 70% of the dishes. These are distributed in a two-dimensional fashion with a Gaussian distribution with a mean dispersion of 300 m, a shortest baseline of 29 m and a longest baseline of 1km.
An outer component containing 30% of the dishes. These are also distributed in a two-dimensional Gaussian distribution with a mean dispersion of 2,500 m and a longest baseline of 8km.
Construction schedule
The pedestal of the first MeerKAT telescope in 2014
Construction of the MeerKAT Precursor Array (MPA – also known as KAT-7), on the site started in August 2009.[8] In April 2010 four of the seven first dishes were linked together as an integrated system to produce its first interferometric image of an astronomical object. In Dec 2010, there was a successful detection of very long baseline interferometry (VLBI) fringes between the Hartebeesthoek Radio Astronomy Observatory 26 m dish and one of the KAT-7 dishes.[9]
Despite original plans to complete MeerKAT by 2012,[10] construction was suspended in late 2010 due to budget restructure. Science Minister Naledi Pandor denied the suspension marked any setback to the SKA project or 'external considerations'.[11] MeerKAT construction received no funding in 2010/11 and 2011/12.[12] The 2012 South African National Budget projected that just 15 MeerKAT antennas would be completed by 2015.[13]
The last of the reinforced concrete foundations for the MeerKAT antennas was completed on 11 February 2014. Almost 5000 m3 of concrete and over 570 tonnes of steel were used to build the 64 bases over a 9-month period.[14]
MeerKAT is planned to be completed in three phases. The first phase will include all the antennas but only the first receiver will be fitted. A processing bandwidth of 750MHz is available. For the second and third phases, the remaining two receivers will be fitted and the processing bandwidth will be increased to at least 2GHz, with a goal of 4GHz. With construction of all sixty-four MeerKAT antennas complete, verification tests have begun to ensure the instruments are functioning correctly.[15] Following this, MeerKAT will be commissioned in the second half of 2018 with the array then coming online for science operations.
Inauguration
On 13 July 2018, the Deputy President of South Africa, David Mabuza, inaugurated the MeerKAT Telescope, and unveiled an image produced by MeerKAT that revealed unprecedented detail of the region surrounding the supermassive black hole at the centre of our Milky Way Galaxy.
The 64 MeerKAT antennas will be incorporated into Phase 1 of the SKA Mid Frequency Array once the 133 SKA dishes have been built and commissioned on the Karoo site, resulting in a total of 197 antennas for the SKA array. All of the infrastructure currently associated with MeerKAT will be transferred to the SKA array. The KAPB has the capacity to house the additional equipment required by SKA Mid.
MeerKAT Phasing schedule
2011 Precursor (KAT-7)
2016 MeerKAT Phase 1
2018 MeerKAT Phase 2 and 3
Number of dishes
7
64
64
Receiver bands (GHz)
0.9 – 1.6
1.00 – 1.75
0.58 – 1.015 0.9 - 1.67 8 – 14.5
Max processed BW (GHz)
0.256
0.75
2 (goal 4)
Max baseline (km)
0.2
8
20
Min baseline (m)
20
29
29
Science objectives
The science objectives of the MeerKAT surveys are in line with the prime science drivers for the first phase of the SKA, confirming MeerKAT's designation as an SKA precursor instrument. Five years of observing time on MeerKAT have been allocated to leading astronomers who have applied for time to do research.
Site
The South African Department of Science and Technology, through the NRF and SARAO, has invested more than R760 million in infrastructure on the South African SKA site. The innovative design and engineering of the infrastructure established for MeerKAT, as well as the RFI-quiet environment, favourable physical site characteristics, and on-site technical expertise has positioned the site in the Karoo as an ideal location for other radio astronomy experiments.
The HERA (Hydrogen Epoch of Reionisation Array) radio telescope is one such instrument co-located at the South African SKA site. HERA is designed to detect, for the first time, radio signals from the very first stars and galaxies that formed early in the life of the universe. South African engineers and scientists are working with their colleagues at the University of California Berkeley in the US, and Cambridge University in the UK, to build HERA and exploit its unique and fundamental scientific capabilities.
Other experiments which have been constructed at the SA SKA site include PAPER (the Precision Array to Probe the Epoch of Ionisation) and the C-BASS (the C-Band All Sky Survey).
To ensure long term viability of the Karoo site for the MeerKAT and the SKA, and for other radio astronomy instruments, the South African Parliament passed the Astronomy Geographic Advantage Act, in 2007. The act gives the Minister of Science and Technology the authority to protect areas, through regulations, that are of strategic national importance for astronomy and related scientific endeavours.
Discoveries
In September 2019, an international team of astronomers using South Africa’s MeerKAT radio telescope discovered enormous balloon-like structures that tower hundreds of light-years above and below the centre of our galaxy.[16]
South Africa and SKA science and technology
The experience gained by South African engineers in the design and construction of MeerKAT had been carried over to the SKA design, reducing risks and development costs. South African engineers within SARAO and South African industrial partners have participated in 7 of the 11 SKA engineering design consortia, contributing about 10% of the workforce in these internationally distributed consortia. The Infrastructure South Africa Consortium and the Assembly, Integration, Verification (AIV) Consortium have been led by SARAO, and there was South African participation in the DISH Consortium, Science Data Processor (SDP) Consortium, the Signal and Data Transport (SaDT Consortium), the Telescope Manager (TM) Consortium and the Mid-frequency Aperture Array Consortium. South African engineers have overseen the system engineering aspects of 5 of the consortia. SARAO has signed an MoU with the SKAO to provide resources to the Bridging Activities that will continue the development of SKA subsystems now that the consortia have concluded their work. Participation by South African industrial partners in previous consortium work and future Bridging Activities is facilitated by SARAO through the Financial Assistance Programme (FAP) funding initiative.
Scientists from SARAO and South African universities are well represented on the various SKA Science Working Groups (SWGs), with about 10% of the authors of papers in the SKA Science Book having South African institution affiliations. The MeerKAT Large Science Projects (LSPs) are closely aligned with the SKA science case, and there is a large membership overlap between the LSP teams and the associated SWGs.
Capacity development for radio astronomy in Africa
To create the required skills to design, construct and operate the SKA and MeerKAT telescopes, and to make optimal use of these radio telescopes for research, once commissioned, SARAO initiated a capacity development programme, in 2005. The programme is fully integrated into the operations of SARAO, and it is crafted to develop and retain the excellent researchers, engineers and artisans required to ensure that the MeerKAT and SKA will be successful in South Africa. To date the programme has provided more than 1000 scholarships and fellowships across all relevant academic levels, and for a range of relevant qualifications. The programme is coveted by academic colleagues from abroad because of its success in developing, from a low base, significant expertise in radio astronomy over the past 14 years.
MESMER (MeerKAT Search for Molecules in the Epoch of Reionization) – Searching for CO at high red-shift (z>7) to investigate the role of molecular hydrogen in the early universe.
MeerKAT Absorption Line Survey for atomic hydrogen and OH lines in absorption against distant continuum sources (OH line ratios may give clues about changes in the fundamental constants in the early universe).
MHONGOOSE (MeerKAT HI Observations of Nearby Galactic Objects: Observing Southern Emitters) – Investigations of different types of galaxies, dark matter and the cosmic web.
MeerGAL (MeerKAT High Frequency Galactic Plane Survey) – Galactic structure and dynamics, distribution of ionised gas, recombination lines, interstellar molecular gas and masers.
Dr Mark Thompson, University of Hertfordshire, United Kingdom Dr Sharmila Goedhart, SKA South Africa, South Africa
MIGHTEE (MeerKAT International GigaHertz Tiered Extragalactic Exploration survey) – Deep continuum observations of the earliest radio galaxies.
ThunderKAT (The Hunt for Dynamic and Explosive Radio Transients with MeerKAT) – e.g. gamma-ray bursts, novae and supernovae, plus new types of transient radio sources.
African Very Long Baseline Interferometry Network (AVN)
The African Very Long Baseline Interferometry (VLBI) Network (AVN) is an important development towards building SKA on the African Continent. The AVN programme will transfer skills and knowledge in the SKA African partner countries (Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, and Zambia) to build, maintain, operate and use radio telescopes.
MeerKAT will also participate in global VLBI operations with all major radio astronomy observatories around the world and will add considerably to the sensitivity of the global VLBI network. Further potential science objectives for MeerKAT are to participate in the search for extraterrestrial intelligence and collaborate with NASA on downloading information from space probes.
A radio telescope is a specialized antenna and radio receiver used to detect radio waves from astronomical radio sources in the sky. Radio telescopes are the main observing instrument used in radio astronomy, which studies the radio frequency portion of the electromagnetic spectrum emitted by astronomical objects, just as optical telescopes are the main observing instrument used in traditional optical astronomy which studies the light wave portion of the spectrum coming from astronomical objects. Unlike optical telescopes, radio telescopes can be used in the daytime as well as at night.
The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes deployed in 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 the Milky Way's center, probed the Universe's cosmological parameters, and provided new knowledge about the physical mechanisms that produce radio emission.
The Square Kilometre Array (SKA) is an intergovernmental radio telescope project being planned to be built in Australia (low-frequency) and South Africa (mid-frequency). The combining infrastructure, the Square Kilometre Array Observatory (SKAO) is located in the United Kingdom. Conceived in the 1990s, and further developed and designed by the late-2010s, when completed sometime in the 2020s it will have a total collecting area of approximately one square kilometre. It will operate over a wide range of frequencies and its size will make it 50 times more sensitive than any other radio instrument. It will require very high performance central computing engines and long-haul links with a capacity greater than the global Internet traffic as of 2013. If built as planned, it should be able to survey the sky more than ten thousand times faster than before.
The Low-Frequency Array, or LOFAR, is a large radio telescope, with an antenna network located mainly in the Netherlands, and spreading across 7 other European countries as of 2019. Originally designed and built by ASTRON, the Netherlands Institute for Radio Astronomy, it was first opened by queen Beatrix of The Netherlands in 2010, and has since been operated on behalf of the International LOFAR Telescope (ILT) partnership by ASTRON.
Owens Valley Radio Observatory (OVRO) is a radio astronomy observatory located near Big Pine, California (US) in Owens Valley. It lies east of the Sierra Nevada, approximately 350 kilometers (220 mi) north of Los Angeles and 20 kilometers (12 mi) southeast of Bishop. It was established in 1956, and is owned and operated by the California Institute of Technology (Caltech). The Owens Valley Solar Array portion of the observatory has been operated by New Jersey Institute of Technology (NJIT) since 1997.
South African Astronomical Observatory (SAAO) is the national centre for optical and infrared astronomy in South Africa. It was established in 1972. The observatory is run by the National Research Foundation of South Africa. The facility's function is to conduct research in astronomy and astrophysics. The primary telescopes are located in Sutherland, which is 370 kilometres (230 mi) from Observatory, Cape Town, where the headquarters is located.
ASTRON is the Netherlands Institute for Radio Astronomy. Its main office is in Dwingeloo in the Dwingelderveld National Park in the province of Drenthe. ASTRON is part of the institutes organization of the Dutch Research Council (NWO).
The Hartebeesthoek Radio Astronomy Observatory (HartRAO) is a radio astronomy observatory, located in a natural bowl of hills at Hartebeesthoek just south of the Magaliesberg mountain range, Gauteng, South Africa, about 50 km west of Johannesburg. It is a National Research Facility run by South Africa's National Research Foundation. HartRAO was the only major radio astronomy observatory in Africa until the construction of the KAT-7 test bed for the future MeerKAT array.
The Algonquin Radio Observatory (ARO) is a radio observatory located in Algonquin Provincial Park in Ontario, Canada. It opened in 1959 in order to host a number of the National Research Council of Canada's (NRC) ongoing experiments in a more radio-quiet location than Ottawa.
The Medicina Radio Observatory is an astronomical observatory located 30 km from Bologna, Italy. It is operated by the Institute for Radio Astronomy of the National Institute for Astrophysics (INAF) of the government of Italy.
The Murchison Widefield Array (MWA) is a joint project between an international consortium of organisations to construct and operate a low-frequency radio array. 'Widefield' refers to its very large field of view. Operating in the frequency range 70–300 MHz, the main scientific goals of the MWA are to detect neutral atomic Hydrogen emission from the cosmological Epoch of Reionization (EoR), to study the sun, the heliosphere, the Earth's ionosphere, and radio transient phenomena, as well as map the extragalactic radio sky. It is located at the Murchison Radio-astronomy Observatory (MRO).
The Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Mid West region of Western Australia. It is operated by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and forms part of the Australia Telescope National Facility. Construction commenced in late 2009 and first light was in October 2012.
The Murchison Radio-astronomy Observatory (MRO) was established by CSIRO in 2009. It lies in a designated radio quiet zone located near Boolardy Station in the Murchison Shire of Western Australia, about 800 kilometres (500 mi) north of Perth on the traditional lands of the Wajarri peoples.
The Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) is a radio interferometer funded by the National Science Foundation to detect 21 cm hydrogen (HI) fluctuations occurring when the first galaxies ionized intergalactic gas at around 500 Million years after the Big Bang. PAPER is a focused experiment aimed toward making the first statistical detection of the 21 cm reionization signal. Given the stringent dynamic range requirements for detecting reionization in the face of foregrounds that are five orders of magnitude brighter, the PAPER project is taking a carefully staged engineering approach, optimizing each component in the array to mitigate, at the outset, any potentially debilitating problems in subsequent data calibration and analysis. This staged approach addresses the observational challenges that arise from very-wide-field, high-dynamic-range imaging over wide bandwidths in the presence of transient terrestrial interference. PAPER began as a collaboration between Don Backer of the UC Berkeley Radio Astronomy Laboratory and Richard Bradley of the National Radio Astronomy Observatory. With Backer's passing in 2010, Aaron Parsons has assumed leadership of PAPER on the side of UC Berkeley.
KAT-7 is a radio telescope situated in the Meerkat National Park, in the Northern Cape of South Africa. Part of the Karoo Array Telescope project, it is the precursor engineering test bed to the larger MeerKAT telescope, but it has become a science instrument in its own right. The construction was completed in 2011 and commissioned in 2012. It also served as a technology demonstrator for South Africa's bid to host the Square Kilometre Array. KAT-7 is the first Radio telescope to be built with a composite reflector and uses a stirling pump for 75 K cryogenic cooling. The telescope was built to test various system for the MeerKAT array, from the ROACH correlators designed and manufactured in Cape Town, now used by various telescopes internationally, to composite construction techniques. With the short baselines the telescope is suited to observing diffuse sources, but will begin VLBI observation in 2013.
The C-Band All Sky Survey (C-BASS) is a radio astronomy project that aims to map the entire sky in the C Band (5 GHz). It has been conducted on two radio telescopes, one operating in the Karoo in South Africa, the other at Owens Valley Radio Observatory in California.
The Large Latin American Millimeter Array (LLAMA) is a single-dish 12 m Nasmyth optics antenna which is under construction in the Puna de Atacama desert in the Province of Salta, Argentina. The primary mirror accuracy will allow observation from 40 GHz up to 900 GHz. It is also planned to install a bolometer camera at millimeter wavelengths. After installation it will be able to join other similar instruments to perform Very Large Base Line Interferometry or to work in standalone mode. Financial support is provided by the Argentinian and Brazilian governments. The total cost of construction, around US$20 million, and operation as well as the telescope time use will be shared equally by the two countries. Construction planning started in July 2014 after the formal signature of an agreement between the main institutions involved.
The Hydrogen Epoch of Reionization Array (HERA) is a radio telescope dedicated to observing large scale structure during and prior to the epoch of reionization. HERA is a Square Kilometre Array (SKA) precursor instrument, intended to observe the early universe and to assist in the design of the full SKA. Along with MeerKAT, also in South Africa, and two radio telescopes in Western Australia, the Australian SKA Pathfinder (ASKAP) and the Murchison Widefield Array (MWA), the HERA is one of four precursors to the final SKA. It is located in the Meerkat National Park.
The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) is an interferometric array of 1024 6-meter (20ft) diameter radio telescopes, operating at 400-800MHz, that will be deployed at the Square Kilometer Array site in the Karoo region of South Africa. The array is designed to measure red-shifted 21-cm hydrogen line emission on large angular scales, in order to map out the baryon acoustic oscillations, and constrain models of dark energy and dark matter.
Meerkat National Park is a large National Park in the Northern Cape, South Africa, that encompasses the Square Kilometre Array, MeerKAT and HERA telescopes. To ensure long term viability of the Karoo site for the MeerKAT and the SKA, and for other radio astronomy instruments, the South African Parliament passed the Astronomy Geographic Advantage Act, in 2007. The act gives the Minister of Science and Technology the authority to protect areas, through regulations, that are of strategic national importance for astronomy and related scientific endeavours. The park does not allow visitors.
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