KAT-7 pics a boost for SKA bid

The MeerKAT precursor array, also known as KAT-7, has produced its first interferometric image of an astronomical object.

Square Kilometre Array (SKA) engineers linked the first four of the seven radio telescopes that were built for the project - an operational telescope and an engineering test-bed for the SKA telescope, according to the Department of Science and Technology (DST).

The four linked telescopes formed an integrated system to produce the interferometric image of an astronomical object - the Centaurus A galaxy, says SKA SA.

The department explains that interferometry refers to the astronomy technique in which radio signals collected at the same time by a system of networked radio telescopes are processed into a high-resolution image.

DST spokesman Tommy Makhode says these are not the first pictures produced by KAT-7.

“In December 2009, the first combined signals (or 'fringes') were obtained from a range of celestial radio sources, using the first two fully equipped antennas. Then the first raster scan image was produced in March 2010 by scanning individual antennas across the Centaurus A radio galaxy (see figure one, left panel).”

SKA SA says this provided a successful end-to-end demonstration of antenna hardware, system stability, pointing accuracy and software.

Once it was evident that the antennas worked well individually, phase closure was achieved, which is the use of three antennas. Amplitude closure was also achieved, which consists of the use of four antennas. Simply put, since the underlying system was working, antennas could be linked together.

SKA SA says the antennas of the four telescopes were linked together to view the Centaurus simultaneously. The signals that were collected by the radio antennas were processed by electronics and control software to transform the four antennas into a single, high-resolution telescope system, called an interferometer.

"We are extremely pleased by the rapid progress and early results obtained from the first four MPA antennas," reports SKA SA project director Dr Bernie Fanaroff. "This shows that we are well on track with the development of our SKA site, and the development of the systems and understanding required to build and operate advanced scientific instruments such as MeerKAT and the SKA. We have a world-class team and we are proud of them."

The DST says the interferometric radio could be handed over to astronomers who could begin to do science with it; science that was not possible in Africa before.

“It is important in terms of the African bid to host what will be the world's largest radio telescope, the SKA, because it demonstrates that Africans have the technical expertise to build such a complex working instrument. This will increase our chances of winning the SKA bid.”

DST spokesman Lunga Ngqengelele adds that the SKA will attract scientists and engineers to Africa, to work on the telescope.

“The KAT-7 will serve as both an engineering test-bed and as an operational radio telescope. The MeerKAT will be one of the largest scientific research facilities in the world and will consolidate Africa as a major global hub for astronomy in the world,” says the DST.

“It will provide unrivalled opportunities for scientists and engineers from across Africa to engage with transformational science and cutting-edge instrumentation, as well as to collaborate in joint projects with the most renowned universities and research institutions in the world.”

“We have started with seven dishes and the next step is to build 80. But this will be done on an incremental basis,” says Ngqengelele.

He explains that the seven dishes of the KAT-7 are now operational, but the next 80 dishes will only be built if SA gets the bid for the SKA.

The results of the bid will be announced in 2012, he notes.