The Square Kilometre Array (SKA) Observatory (SKAO) has announced the successful conclusion of a key test of its South Africa-based SKA-Mid instrument. The SKA-Mid (Mid being short for mid radio frequency), being constructed in the Karoo region in the Northern Cape province, would, when completed, be composed of 197 dishes (including those of South Africa’s established MeerKAT radio telescope array, which was ultimately intended to be integrated into the SKA-Mid array).

The test saw two of the seven SKA-Mid dishes so far assembled, work together as an interferometer for the first time. Their target was a radio galaxy located some 2.6-billion light years from Earth.

“This is the first true test that all our systems are working together, and that all our systems are working together, and that the SKA-Mid telescope is alive as a scientific instrument,” highlighted SKAO director-general Professor Philip Diamond. “Having each dish observe the sky individually is an achievement but having them operate in concert as one telescope is a much bigger technical challenge, and our teams have now achieved that milestone.”

Interferometry involved pointing two or more radio telescope antennas on the same object in the sky and then combining the data they received, creating the effect of an observation by a much larger telescope. When data was successfully combined, the result was known as “fringes”. This test of the SKA-Mid thus achieved “first fringes”.

“Starting this the year with this news is a huge boost for the teams that have worked extremely hard to see it happen, including SKAO and [South African Radio Astronomy Observatory] colleagues, and our global and local partners who are contributing to the infrastructure, hardware and software for SKA-Mid,” enthused SKA-Mid Senior Project Manager Ben Lewis. “With all we’ve learned from these months building up to first fringes, we’re in a strong position to achieve our next milestone – the first image from a four-dish array within the next few months – and then see SKA-Mid gradually grow in size and capabilities from there.”

The other element of the SKA was the low-frequency instrument, SKA-Low, being deployed in Australia. The SKA-Low, which was composed of simple antennas, grouped into “stations” of 256 antennas each, achieved its first image last year (2025). This was obtained by 1 024 antennas in four stations, which was less than 1% of the size the array would be, when completed.