Name of the Project
MeerKAT telescope project.

Location
Northern Cape, South Africa.

Client
The Square Kilometre Array South Africa (SKA SA) is the agency that drove South Africa’s bid to host the €1.5-billion international SKA radio telescope and the MeerKAT programme.

Project Description
South Africa’s MeerKAT radio telescope array is intended to be a precursor of the international SKA radio telescope. The MeerKAT evolved from the original idea of a Karoo Array Telescope.

The reference design specification for the full MeerKAT is 64 offset dishes, each with a diameter of 13.5 m, with single-pixel wideband feeds covering the 500 MHz to 2.5 GHz frequency range. The design means that there are no struts over the dish, which can reduce or scatter incoming radio waves, thus increasing the sensitivity of the antenna.

The completed MeerKAT will have a central core, but some dishes are almost 10 km apart, thus replicating the SKA on a small scale.

It will also facilitate the installation of multiple receiver systems in the primary and secondary focal areas and is the reference design for the midband SKA concept.

The MeerKAT will be delivered in three phases.

The first phase – the MeerKAT Precursor Array, known as KAT-7 and which comprises seven 12-m-diameter composite parabolic dishes at the Karoo site – was completed in 2010.

This prototype interferometer array serves as an engineering test-bed for technologies and systems, and as an operational radio telescope. MeerKAT is designed to be integrated into the SKA radio telescope, which will be cohosted by South Africa and Australia.

Value
The estimated cost is R900-million.

Duration
The commissioning of MeerKAT is scheduled for 2014/15, with the array coming on line for science operations in 2016. This phase includes all antennas, but only the first receiver will be fitted, and a processing bandwidth of 750 MHz will be available.

For MeerKAT Phase 2 and Phase 3, the remaining two receivers will be fitted and the processing bandwidth will be increased to at least 2 GHz and later to 4 GHz.

Latest Developments
Although still under construction, the MeerKAT radio telescope array has successfully participated in an unprecedented international collaboration that has opened a new era in astronomy. For the first time, a major astronomical event – the collision of two neutron stars – has been observed in the electromagnetic spectrum and by gravity waves.

The US Laser Interferometer Gravitational Wave Observatory (Ligo), comprising two sets of detectors, at Hanford, in Washington, and Livingston, in Louisiana, detected a gravitational wave source (designated GW170817) on August 17. Almost immediately afterwards, the same wave was detected by the six-country European collaborative Virgo gravity wave observatory, near Pisa in Tuscany, Italy, and about two seconds later, the US National Aeronautics and Space Agency’s Fermi space telescope detected a gamma ray burst from the same area.

The observations by the three gravity wave detectors on two continents, followed by the observation of the gamma ray burst by the space telescope, allowed for a triangulation of the source. This, in turn, permitted follow-up observations by some 70 optical, infrared, ultraviolet, radio and X-ray telescopes on earth and in space.

One of the radio astronomy instruments involved was MeerKAT, which observed the event from August 26 to September 17.

The phenomenon was also observed by the Southern African Large (optical) Telescope and the Hartebeesthoek Radio Astronomy Observatory (HartRAO) – MeerKAT and HartRAO both form part of the recently established South African Radio Astronomy Observatory (Sarao).

“[T]he initial observations we’re making of GW170817 indicate that we’re already contributing meaningfully in this area . . . even as we’re still building it, MeerKAT has started to do science,” Sarao chief scientist Dr Fernando Camilo has highlighted.

“The Ligo-Virgo gravitational wave detection and subsequent electromagnetic study of the binary neutron star collision is one of the many truly wondrous moments of modern astrophysics,” he has contended. “Many of us have dreamt about this event for decades, and it’s more wonderful than we could have imagined. It raises as many questions as it begins to answer.”

“Deep understanding in this area will come from continued study of the electromagnetic radiation from the remnant of GW170817, which we expect to evolve over weeks and months; and from the detailed study of more such events to follow in the years to come,” he has pointed out. “Currently, the radio waves from this source are too faint for the partially built MeerKAT to detect, but our sensitivity at the radio frequency we use is already among the best in the world, and our scientists and engineers in South Africa are working hard on making it even better.”

The collision took place relatively close to earth, in astronomical terms – at a distance of 130-million light years. The two neutron stars spiralled into each other. Each had a mass estimated at between 1.1 to 1.6 times the mass of the sun.

Neutron stars are the smallest and most dense stars known. Each is only about 20 km in diameter, but a neutron star is so dense that a teaspoon-full of its matter would have a mass of a billion tons. For the last 100 seconds before they collided, the two neutron stars emitted gravitational waves that were detected on earth and when they smashed into each other they emitted a burst of gamma rays. Other forms of electromagnetic radiation, including visible light, were also released and detected in the following days and weeks.

“This detection opens the window of a long-awaited ‘multimessenger’ astronomy,” highlighted Ligo Laboratory executive director David H Reitze. “It’s the first time we’ve observed a cataclysmic astrophysical event in . . . gravitational waves and electromagnetic waves – our cosmic messengers.”

Key Contracts and Suppliers
Group Five Coastal (building foundations); Schneider Electric South Africa (building management system); Stratosat Datacom (part of Germany’s Schauenburg Group), with its technology partners, General Dynamics Satcom, of the US, and Vertex Antennentechnik, of Germany (design, construction, installation and commissioning of antennas); Efficient Engineering (antenna pedestals and yokes); Tricom Structures (backup structures for dishes); Titanus Slew Rings (main azimuth bearings); National Research Council of Canada (low-noise amplifiers); Oxford Cryosystems (cryogenic cooling system); Brink & Heath Civils (foundations); and Max-Planck-Society and Max Planck Institute for Radio Astronomy (S-band radio-wave receivers).

On Budget and on Time?
The project is on schedule.

Contact Details for Project Information
MeerKAT engineering office, tel +27 21 506 7300 or fax +27 21 506 7375.