Science imminent at Klerefontein


Astronomy will soon get underway at Klerefontein in the Groot Karoo where the first two 12-metre 4.5mt MeerKAT Precursor Array (MPA) dishes are now operational and have measured their first interference fringes.

The MPA, previously the KAT-7 (seven dish Karoo Array Telescope) is being erected at a remote site some 5km north of Klerefontein, itself about 78km north of Carnarvon

The MPA is the prototype for a larger 80-dish MeerKAT (more-than-KAT) that is scheduled to be completed by December 2012 and commissioned in 2013. MeerKAT is set to cost R860 million and forms part of the R1.6 billion budget Cabinet last month approved for the country to win the right to host the 3000 to 5000-dish 1.5 billion euro (R160 billion) Square Kilometre Array (SKA).

The first dish was erected in July and the entire installation should be complete by next month, South African SKA Project director Dr Bernie Fanaroff says.

He adds that to date four of the MPA’s seven BAE Systems-built dishes have been erected. Two have been fitted with their receivers and digital back-ends that will receive and process celestial radio.

Engineering News recently reported that it was these two dishes, working together to create an interferometer, that detected the fringes.

The engineering journal explained that interferometry involves using two or more radio telescope dishes to look at the same object in the sky. “The signals received by each dish are fed into a computer and because the dishes are not in exactly the same place (even if they they are only a few tens of metres apart) the distance travelled by the signals to each is not identical and combining them creates an interference pattern – the fringes – that can be analysed by computer to provide high-resolution images of celestial objects.”

It said the detection of the fringes “proves that the entire MPA system, from the dishes in the Karoo receiving the radio waves from space, to the final processing computers in the control centre in Cape Town, works. All the different elements in the system had been tested individually, but this was the first time the whole system was tested for real.”
“The first-time success of the test is partly due to the creation, testing and evaluation of a replica system at the MeerKAT offices in Cape Town, although of course this replica does not have any dishes,” the Engineering News added.
“It should be pointed out that this test was an engineering test, not a scientific one, and is only the beginning of a long test programme. That the MPA works has been demonstrated, but its operational performance still has to be determined.”

Fanaroff told defenceWeb the detection of interference fringes “are the most basic product of an array (which is an interferometer)”

He added the significance of the early success was that it “is very unusual for an interferometer system to work so quickly and so well after assembly on site, which proves the efficacy of the system engineering process and the world-class competence of the MeerKAT team.”

MeerKAT and the SKA are expected to have a service life of at least 30 years.