SKA-Mid prototype dish creates first light image

The prototype, which is a fully functioning single-dish radio telescope in its own right, was funded by Germany’s Max Planck Society for technical commissioning and scientific use. It is contributing to the SKA Observatory’s preparations for commissioning the much larger 197-dish SKA-Mid telescope, currently under construction in South Africa.

Known as SKAMPI, it was designed by the SKAO’s international Dish consortium, involving institutions in 10 countries and led by CETC54 in China, where it was also manufactured.

SKAMPI’s first light image of the Southern Sky at 2.5 GHz wavelength demonstrates that the technology is working as expected, and although the uncalibrated measurements are still affected by radio frequency interference (RFI), atmospheric and system variations, the image already reveals much of the characteristic radio emission of our Milky Way and external galaxies such as Centaurus A. The team also tested out the dish’s pulsar mode, detecting the Vela pulsar. 

Above: First light SKAMPI image of the Southern Sky at 2.5 GHz wavelength. The frame (in grey) shows the complete sky in galactic coordinates with the Galactic centre in the middle. The false colour image shows radio emission from the part of the sky which is accessible to the telescope in South Africa. Besides radio emission from the Galactic centre (Sgr A), the bright radio galaxy Cen A, both Magellanic clouds and star forming areas in Orion and Vela show up in the image. Credit: SKAMPI Team

“Tests of the SKAMPI prototype have already provided invaluable measurements of key performance parameters. These have been used to refine the design of the SKA-Mid dishes to ensure that they meet our demanding requirements for pointing and surface accuracy,” said SKAO Head of System Science Dr Robert Laing.

“The test procedures developed for SKAMPI will also be used to qualify the new SKA-Mid dishes before they are integrated into the array.”

SKAMPI was fully assembled in mid-2018 at the South African SKA site in the Karoo by the Max Planck Institute for Radio Astronomy (MPIfR), OHB Digital Connect GmbH and the South African Radio Astronomy Observatory (SARAO). Initial test observations took place in December 2019 and technical commissioning such as system evaluation, radio frequency interference testing and performance testing took place until early 2022, leading to the SKA system design qualification documents published later that year.

SKAMPI will enter full science operations later this year, with further technical developments planned.

Although much of its observing time will be dedicated to science programmes defined by the SKAMPI team, requests for observations will also be open to the South African and German science communities, and setting up an educational programme for schools and universities is under consideration.