The South African Radio Astronomy Observatory (SARAO) announced on Tuesday that its MeerKAT radio telescope array had for the first time, and successfully, participated in a regular international Very Long Baseline Interferometry (VLBI) observation with the European VLBI Network (EVN). Work to integrate MeerKAT into the EVN started in 2022 and involved a series of tests before full operational status was reached.

To put it simply, VLBI involved pointing widely separated radio telescopes at the same object or phenomenon in the sky at the same time, and all simultaneously recording the data they received. This data was then combined. The effect was as if a single radio telescope of enormous size had studied the object concerned. The radio telescopes in the VLBI network can be in different countries, different continents and, as in this case, different hemispheres.

The EVN fell under the European Research Infrastructure Consortium (ERIC) and was operated by the Joint Institute for VLBI ERIC (JIVE). South Africa’s 26 m radio telescope at Hartebeesthoek, west of Pretoria, has been part of EVN for many years now. The EVN also included radio telescopes in China and South Korea and had a baseline that could extend up to 9 000 km, making it the world’s most sensitive VLBI network.

MeerKAT is currently composed of 64 dishes, each with a diameter of 13.5 m, spread across an area of 8 km, in the Karoo region in the Northern Cape province. It is a precursor to the mid-frequency array of the international Square Kilometre Array (SKA-Mid) radio telescope, currently being built alongside it. In due course, MeerKAT will be integrated into SKA-Mid. The international array will be owned and operated by the SKA Observatory (SKAO).

“MeerKAT has been highly successful in its mission to explore the radio sky in unprecedented detail, imaging some of the largest-scale structures in the universe,” highlighted SARAO MD Pontsho Marupeng. “At the same time, we place strong emphasis on collaborating with other instruments as we continue to develop MeerKAT’s scientific capabilities before its eventual integration into the SKA-Mid telescope. We’re excited about the collaboration with our JIVE colleagues, using the power and versatility of MeerKAT, alongside other telescopes in the EVN network, harnessing the power of VLBI to target the most compact objects and reveal their finest details.”

The object imaged in this joint MeerKAT-EVN observation was a supermassive block hole, designated J0123+3044. This ejected “jets”, that is, streams of high-energy particles, visible only at radio wavelengths. The extra sensitivity provided by MeerKAT has allowed the astronomers to “decipher” the structure of these jets, which could not previously be done by the EVN on its own.

“This is a great achievement by the SARAO team, enabling MeerKAT to observe together with the EVN,” affirmed JIVE Council chairperson Jessica Dempsey. “It marks an important milestone in the expansion of the global VLBI network – where arrays such as the EVN, MeerKAT, and soon the SKAO will work in synergy. This collaboration not only showcases the power of international partnerships in radio astronomy but also paves the way for transformative scientific discoveries through cutting-edge technological innovation.”