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African Star Joins the Radio Astronomy Firmament

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African Star Joins the Radio Astronomy Firmament mission control African star joins the radio astronomy frmament A powerful new radio telescope will improve our understanding of galaxy formation and evolution, and other key questions in astrophysics, says Fernando Camilo, on behalf of the MeerKAT team. fter a decade in the works, South Africa’s MeerKAT telescope (Fig. 1), Aa precursor to the Square Kilometre Array (SKA) mid-frequency telescope, is beginning science operations. MeerKAT is a radio interferometer located in the semi- arid and sparsely populated Karoo region of the Northern Cape. The array consists of 64 antennas 13.5 m in diameter located on baselines of up to 8 km. The distribution of the antennas, with three quarters of them located within a 1-km-diameter core, makes MeerKAT Fig. 1 | Part of the 64-dish MeerKAT array. Credit: South African Radio Astronomy Observatory particularly suited to a variety of pulsar and neutral hydrogen studies. Several of the selected large survey projects (LSPs), which correlator/beamformer processes the 2 computing power deployed at the KAPB, will use two thirds of the available observing Tbps of data arriving from 64 dishes in and 40 PB of storage at the Centre for time within five years, will address key real time. The correlator is based on the High Performance Computing in Cape questions related to galaxy formation CASPER (Collaboration for Astronomy Town, where the permanent MeerKAT and evolution. For instance, the unique Signal Processing and Electronics Research) archive resides. Efficiency in both power combination of column density sensitivity architecture, using Ethernet switches to and cost has been the dominant driving and angular resolution will make MeerKAT handle data transfer between processing factor behind these solutions. For instance, a powerful probe for studying accretion onto nodes. For MeerKAT, the processing nodes careful specification, in-house integration galaxies in the nearby Universe. Projects consist of SKARAB (SKA Reconfigurable and co-design with the software stack have will investigate the range of conditions from Application Board) boards populated with yielded a massive-scale, high-performance star-forming disks to low-density gas in dark field-programmable gate arrays, developed storage cluster for a fifth of the cost of matter haloes in isolated galaxies, and will at SKA South Africa. comparable commercial options. examine how galaxies interact within rich The flexibility of the MeerKAT MeerKAT is a South African-funded clusters, while seeking to detect the cosmic architecture enables the deployment project, largely designed and built in South web. Further afield, the 21-cm line of neutral of multiple guest instruments that can Africa. It is the result of an integrated plan hydrogen will be used to investigate the subscribe to telescope data streams and that included careful consideration of properties and evolution of galaxies across simultaneously process them in a bespoke multiple design options, development of two thirds of cosmic time. fashion tuned to each specific scientific technology demonstrators, training and Although optimized for particular requirement. In this way, for instance, while investment in people through a human applications, MeerKAT is an extremely one LSP investigates the evolution of the capital development programme and sensitive general-purpose radio telescope. cosmological star-formation rate density cooperation with industrial partners, and The dishes are of a highly efficient offset (through a continuum survey of selected support from a wide variety of national Gregorian design, with up to four receiver fields), another team searches for fast radio stakeholders. First light occurred in 2016 systems positioned on a turret near the sub- bursts lasting a few milliseconds (which may using 16 antennas; the first science results reflector, without compromising the clean be precisely localized because the back-end were published in April 2018 (F. Camilo et al., optical path. Three cryogenic receivers are forms hundreds of beams tiling the large Astrophys. J. 856, 180; 2018); and data currently being installed: L band (covering primary telescope beam), while yet another collection has begun for the first LSPs using 900–1,670 MHz), UHF (580–1,015 MHz) group searches for artificial signals from 64 antennas. The first call for open time and S band (1.75–3.5 GHz; provided by the extraterrestrial sources. proposals, for one-third of the available Max Planck Institute for Radio Astronomy). The MeerKAT science data processor observing time, is expected in late 2018. The measured sensitivity of one 13.5-m receives up to 300 Gbps from the Eventually, MeerKAT will be MeerKAT antenna at L band is comparable correlator, which it averages in real time integrated into the international SKA to that of a 25-m Jansky Very Large Array after applying appropriate flagging and Phase 1 mid-frequency array. ❐ antenna, with a much larger field of view. calibration solutions. The resulting ~10 The radio-frequency voltages for each Gbps streams are archived, and further Fernando Camilo of two linear polarizations are digitized processed through imaging pipelines South African Radio Astronomy Observatory in a shielded package just 1 m behind the to produce ‘spectral cubes’: maps of sky (SARAO), Cape Town, South Africa. receivers. The samples are then transmitted brightness as a function of frequency. e-mail: [email protected] via buried optical fibre to the Karoo The scale of the computational and Array Processor Building (KAPB), located storage challenge is significant, with 1015 Published online: 3 July 2018 ~10 km away. There, the MeerKAT FX/B floating-point operations per second of https://doi.org/10.1038/s41550-018-0516-y 594 NATURE ASTRONOMY | VOL 2 | JULY 2018 | 594 | www.nature.com/natureastronomy.
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