What is MeerKAT? MeerKAT is a radio telescope array operated by the South African Radio Astronomy Observatory (SARAO), a national facility of the National Research Foundation. It consists of 64 individual dish antennas, each 13.5 metres in diameter, spread across an area of roughly 8 km in the Karoo semi-desert of the Northern Cape. Inaugurated on 13 July 2018 by then Deputy President David Mabuza, it is currently the most sensitive radio telescope array of its kind in the southern hemisphere. The name itself has a pleasing history. The original design was called KAT — the Karoo Array Telescope. When the South African government significantly increased the funding and doubled the number of planned dishes from 20 to 64, the project was renamed MeerKAT: literally more of KAT. In Afrikaans, meer means more. It is, in every sense, a very South African telescope. Each dish is a marvel of precision engineering. The reflector surface must maintain its shape to within a fraction of a millimetre across its full width regardless of temperature, wind loading, or the angle at which it is pointed. The receivers mounted at the focus of each dish are cooled to within a few degrees of absolute zero — colder than deep space itself — to minimise thermal noise and achieve the extraordinary sensitivity the instrument requires. The 64 dishes do not operate independently. Their signals are combined by a powerful correlator — a specialised supercomputer — that processes the data from all dishes simultaneously, effectively creating a single virtual telescope up to 8 km in diameter. This technique, known as aperture synthesis interferometry, is the same principle that makes arrays like the Very Large Array in New Mexico so powerful — and it is a principle that every amateur radio operator who has thought about antenna arrays will find intuitively familiar. A Child of South Africa What makes MeerKAT particularly remarkable is that it was designed and built almost entirely by South African engineers and scientists. The hardware, the software, the signal processing systems — the vast majority of it was conceived, developed and manufactured within South Africa. For a country that sometimes underestimates its own scientific and engineering capability, MeerKAT is a powerful reminder of what is achievable. The telescope is not a standalone project. It was conceived from the outset as the South African precursor instrument to the Square Kilometre Array — the SKA — an international megaproject that will, when complete, become the largest and most powerful radio telescope ever constructed. MeerKAT is both a world-class scientific instrument in its own right and a proving ground for the technologies and techniques that the SKA will depend on. Every radio amateur understands RFI. We have all hunted interference — the switched-mode power supply next door that puts noise across 40m, the solar inverter that kills a quiet band, the laptop charger that raises the noise floor at exactly the wrong moment. Now imagine scaling that problem up to the point where you need to hear a signal so faint it carries less power than a single snowflake landing on your antenna. That is the world MeerKAT lives in — and it is why South Africa did something no other country had ever done on this scale. A Guinness World Record in Silence The Karoo Central Astronomy Advantage Area (KCAAA) is officially the largest radio quiet zone on Earth, a fact confirmed by Guinness World Records. It covers approximately 106,306 square kilometres — an area roughly three times the size of the previous record holder, the United States National Radio Quiet Zone around Green Bank, West Virginia, which covers approximately 33,670 square kilometres. To put it another way: the KCAAA is larger than the entire country of Portugal, or about the size of South Korea. The legal framework behind this silence is the Astronomy Geographic Advantage Act (Act 21 of 2007), passed by the South African parliament on 17 June 2007 — more than a decade before MeerKAT's first dish went live. The regulations came fully into effect in December 2021, establishing a tiered protection system with different levels of restriction depending on distance from the telescope core. How the Zones Work The protection area is not a single uniform zone. It operates in concentric layers, with the most stringent restrictions closest to the telescope core — located 90 km north of Carnarvon — and progressively more relaxed conditions toward the outer boundary.What is Actually Banned? The primary target of the regulations is the radio frequency spectrum from 100 MHz to 25.5 GHz — which covers virtually every frequency band of interest to radio astronomers and, not coincidentally, almost every wireless device in modern life. Within the core zones, the following are either prohibited or tightly controlled:Devices Prohibited or Restricted: • Mobile phones and smartphones • WiFi routers and access points (802.11 any band) • DECT cordless telephones • Bluetooth devices • Microwave ovens (leak on 2.4 GHz) • Solar panel inverters and charge controllers • Switch-mode power supplies of all kinds • LED lighting drivers (switching electronics) • Variable-speed motor drives • Spark-ignition petrol engines (unshielded) • Wind turbines within 50 km (require permit) • Amateur radio transmitters • CB radio • All broadcast transmitters (TV, FM, AM) • Radar and navigation transmitters • Drone remote control systems Why Each One Matters: The common thread connecting every item on that list is unintentional or intentional radio frequency emission. To a radio astronomer, it does not matter whether a device is designed to transmit — only whether it radiates energy in the protected spectrum. A microwave oven leaks on 2.45 GHz — right in the middle of an important hydrogen line. A switching power supply generates broadband hash from kilohertz to gigahertz. A solar inverter, converting DC to AC at high switching frequencies, radiates across much of the spectrum. An LED driver dims its light by rapidly switching the current — and that switching generates radio noise. In the core zone, even the power supply for the telescope itself must be specially engineered and shielded to prevent self-interference. The SKA construction team is currently testing prototype remote solar power stations specifically designed to meet the electromagnetic emission requirements of the radio-quiet site. Farmers within the 50 km radius who wish to use WiFi on their properties, or operate public mobile radio equipment, or install smart electricity meters, must apply for a permit from the Astronomy Management Authority. Those who need a permit to continue existing operations had to register and apply once the regulations came into full effect in December 2021. WHAT MEERKAT HEARS Discoveries from the radio heart of the cosmos In 2023, the Royal Astronomical Society presented MeerKAT's team with its Group Achievement Award — one of the most prestigious honours in British astronomy — for what it called 'spectacular advances in radio astronomy' achieved in a remarkably short period of operation. It was a fitting recognition for an instrument that has, in just a few years, rewritten parts of our understanding of the universe. The Bubbles at the Heart of the Milky Way MeerKAT's most iconic discovery came in September 2019, with the very first scientific result from its complete 64-dish array. Pointing toward the centre of our own galaxy, astronomers discovered two enormous balloon-like radio-emitting structures towering hundreds of light-years above and below the plane of the Milky Way. These radio bubbles, stretching roughly 1,400 light-years across the galactic centre, had been completely hidden from previous telescopes by the blinding glare of radio emission from the galactic plane itself. The structures are believed to be the remnant of a phenomenally energetic eruption that occurred near Sagittarius A* — the four-million solar mass black hole lurking at the centre of our galaxy — several million years ago. Whether triggered by a burst of star formation that sent shockwaves through the galactic centre, or by a feeding frenzy as the black hole devoured vast quantities of gas and dust, the bubbles stand as a monument to an event of almost incomprehensible violence in our galaxy's past. The result was published in Nature and made headlines worldwide. 60 New Cosmic Structures — and Counting In work published in early 2026, MeerKAT researchers identified 103 diffuse radio sources in galaxy clusters, 60 of which had never been detected before by any instrument. These findings illuminate how galaxy clusters — the largest gravitationally bound structures in the universe — evolve, interact and redistribute energy across cosmic scales. Each new structure is a clue to the forces shaping the universe's large-scale architecture. Giants in the Deep MeerKAT has proved to be an exceptional hunter of giant radio galaxies — enormous structures formed when supermassive black holes at the cores of galaxies launch jets of plasma that travel millions of light-years into intergalactic space, lighting up as they go. In January 2025, a team from the University of Cape Town published results revealing new giant radio galaxies discovered with MeerKAT, with co-author Kathleen Charlton noting that the number of such discoveries had 'absolutely exploded' in the preceding five years thanks to MeerKAT's sensitivity. Neutron Stars, Pulsars and Gravitational Waves MeerKAT has been a powerful tool for pulsar science — the study of rapidly rotating neutron stars that emit beams of radio waves with clockwork precision. By monitoring arrays of pulsars spread across the galaxy, astronomers can use them as a detector for gravitational waves — ripples in spacetime caused by the most violent events in the cosmos. MeerKAT contributed to the detection of radio afterglow from a neutron star merger event, earning the RAS Group Achievement Award mention as one of the instrument's headline breakthroughs. Connecting with the World In January 2025, MeerKAT was successfully integrated for the first time with the European VLBI Network (EVN) — the world's most sensitive network of radio telescopes using very long baseline interferometry. The combined system produced the highest-resolution images of a distant black hole jet ever achieved from the southern hemisphere, opening new possibilities for international collaboration and pointing toward what the SKA era will make routine. Growing the Array — MeerKAT+ MeerKAT is not standing still. The MeerKAT+ expansion project, jointly funded by SARAO and Germany's Max Planck Society with support from Italy's Istituto Nazionale di Astrofisica, is adding 14 new dishes to the array. The first dish was delivered in February 2024 and by late 2025, five additional SKA-Mid dishes had joined the array alongside the 64 MeerKAT dishes, bringing the total to 83 antennas. This expanded array, designated SKA-Mid AA1.0, is already delivering improved sensitivity and survey speed We Share These Frequencies If you have ever hunted interference in your own shack, you already understand MeerKAT's fundamental challenge at a human scale. We all know the frustration of a noise source that raises the floor on 40m, or a switching supply that puts hash across a quiet band. Radio frequency interference — RFI — is to radio astronomy exactly what light pollution is to optical astronomy: invisible to those who cause it, catastrophic to those trying to observe through it. MeerKAT listens on frequencies we use. The hydrogen line at 1420.405 MHz — one of the most important frequencies in radio astronomy, used to map the structure of galaxies including our own — sits in the middle of the 23 cm amateur band. The telescope's receivers span from around 580 MHz to 3.5 GHz depending on the feed installed, covering portions of spectrum that amateur allocations share or adjoin. The Karoo's radio quiet zone is not a comment on amateur radio in particular — it applies to everything equally. But it is a vivid demonstration of just how sensitive modern radio receivers can be, and a reminder that our frequencies carry far more than our signals. Every switching power supply, every solar inverter, every LED driver we use radiates into the same spectrum we spend so much effort trying to use cleanly. The Same Ionosphere There is a deeper connection too. The ionosphere that MeerKAT must account for when it observes at certain frequencies — the layer of charged particles that refracts and absorbs radio waves — is the same ionosphere we rely on for DX. The physics of propagation that lets your FT8 signal reach Japan on 10m is the same physics that limits what MeerKAT can observe and when. Radio astronomy and amateur radio are, at a fundamental level, two activities built on the same physical foundation. Radio astronomy has, in fact, given back to amateur radio in practical ways. The development of low-noise amplifiers for radio telescope front ends has influenced receiver design across the industry. WiFi itself — now ironically banned in the Karoo quiet zone — owes its development partly to radio astronomy research conducted in Australia. The technologies flow in both directions. Pride in Our Backyard For South African hams, there is a particular reason to pay attention to MeerKAT: it is ours. Designed here, built here, operated here — by South African scientists and engineers — and now recognised as one of the most productive radio telescopes in the world. The Royal Astronomical Society does not hand out Group Achievement Awards to instruments that are merely good. MeerKAT is genuinely exceptional. And the best is still to come. MeerKAT will eventually be absorbed into SKA-Mid — a 197-dish array centred on the same Karoo site, incorporating the 64 MeerKAT dishes alongside new SKA dishes built to even more exacting specifications. Construction is actively under way. By January 2026, the first SKA-Mid dishes had achieved 'first fringes' — the moment when two dishes first worked together as an interferometer, the equivalent of a first QSO for a new station. First science data from a 64-dish SKA-Mid array is expected by early 2027. The SKA — What Comes Next The Square Kilometre Array will, when complete, be 50 times more sensitive than any radio instrument currently in existence and able to survey the sky more than ten thousand times faster. It will probe the era of cosmic dawn — the period shortly after the Big Bang when the first stars ignited — search for pulsars orbiting the black hole at our galaxy's centre, look for amino acids and complex organic molecules in distant star-forming regions, and potentially detect signs of technological civilisations beyond our solar system. All of this depends on silence. The silence of a quarter-million square kilometres of the Northern Cape, enforced by an Act of Parliament, sustained by the cooperation of farmers, local communities and authorities across a vast and sparsely populated landscape. It is a silence that South Africa chose, deliberately and legislatively, in order to hear the universe more clearly. Closing Thought The next time you are on 40m late at night, spinning the dial through the mix of signals and noise that populates a busy band, spare a thought for sixty-four dishes in the red Karoo dust. They are doing what we do — listening to what the radio spectrum has to tell us — but at a scale and sensitivity that makes our most sensitive receivers look almost crude by comparison. They are listening to the universe. And to do it, South Africa silenced an area the size of Portugal. That is something to be proud of.