The RATT, PARROT and MeerKAT — how EC scientists are unlocking the secrets of the stars

CARNARVON, SOUTH AFRICA ñOCTOBER 9: Five of the seven satellite dishes that make up the KAT radio telescope on October 9, 2012 in Carnarvon, South Africa. The Square Kilometre Array telescope will be built here and it will be the largest telescope in the world. (Photo by Gallo Images / The Times / Halden Krog)

By Estelle Ellis

9 Mar 2025

The researchers are combing through years of data from the MeerKAT telescope to search for radio sources that might have been missed – possibly even hints of extraterrestrial technology.

Researchers from Rhodes University in Makhanda, Eastern Cape, are part of a project to mine the MeerKAT telescope’s archive for previously overlooked transient radio sources in the galaxy. It has been described as Earth’s best chance to date of finding our cosmic neighbours.

Their first two finds were published by the Monthly Notices of the Royal Astronomical Society in February.

The MeerKAT radio telescope is near Carnarvon in the Northern Cape. It consists of 64 dishes, each 13.5m in diameter, and is a precursor to the Square Kilometre Array project that is likely to be completed in 2028 or 2029 and will be the most powerful radio telescope in the world.

Now researchers are combing through six years of MeerKAT telescope data to see if they have missed anything. The team taking another look includes scientists from the Rhodes University Centre for Radio Astronomy Techniques and Technologies (RATT), in partnership with the South African Radio Astronomy Observatory, the Paris Observatory, the Breakthrough Listen Initiative and the universities of Oxford and Cape Town.

Professor Oleg Smirnov from the RATT explained that the telescope is also a powerful tool used by the Breakthrough Listen Initiative to search for technosignatures, or indicators of technology, as a proxy for extraterrestrial intelligence.

“The genesis of this project goes back to our discovery of the RATT PARROT,” Smirnov explained.

“The PARROT is an unusual pulsar that was serendipitously discovered when the team studied the conjunction of Jupiter and Saturn in 2020.

MeerKAT The globular cluster NGC 6624 was captured by the Nasa/ESA Hubble Space Telescope. Some of the pulsars hosted by the by the cluster have been highlighted in the inset: In red, the new pulsar PSR J1823-3021G, found by MeerKAT. The cluster NGC 6624 is located in the constellation of Sagittarius at just under 8,000 light-years from the sun. (Image: South African Radio Astronomy Observatory)

“Observing the two planets passing by, each closer than ever seen before in 400 years, RATT researchers were focusing on Jupiter, but then suddenly they picked up something new and saw a transient radio source suddenly switching on in the vicinity of Saturn. This lasted for about 45 minutes before going out again.

“Such transient sources are very rare and almost always point to something exciting going on,” Smirnov explained at the time.

“Over the next few months, MeerKAT returned to the same location in the sky to try to find the same winking pulsar again. Eventually, MeerKAT found it again. This newfound pulsar was named a PARROT, short for ‘pulsar with anomalous refraction recurring on odd timescales’,” he said.

“Of course, we loved this acronym. The Rat & Parrot has been a favourite watering hole for generations of Rhodes University staff and students. In fact, one of the technical breakthroughs that made this discovery possible started over drinks at the Rat & Parrot. In a way, it felt like we were paying homage to that.”

Smirnov explained that the discovery of the RATT PARROT led them to think that there must be many more transient sources inside the data collected by the MeerKAT.

“Pulsars are the remnants of massive stars that have ended their life in a supernova explosion… It creates two beams of powerful radio emission as it swings around – like a cosmic lighthouse.

“If the Earth happens to be in the path of such a beam, then every time the beam sweeps through – every 1.6 seconds, in the case of the PARROT – we observe a distinct pulse of emission that has given pulsars their name,” Smirnov added.

The radio signal from the PARROT occasionally experiences amplification by factors of 10 or more within minutes.

Smirnov said this is more than a mere twinkle since “no amount of twinkling will brighten a star by a factor of 10 or more”.

Five of the seven satellite dishes that make up the KAT radio telescope in Carnarvon on 9 October 2012. The Square Kilometre Array telescope will be built here and it will be the most powerful radio telescope in the world. (Photo: Gallo Images / The Times / Halden Krog)

Encouraged by finding the PARROT, the team has been working for a year now and has made another two significant findings.

“We found the PARROT through sheer blind luck, then requested a few follow-up observations to get to the bottom of things. Lo and behold, we’ve now caught a flaring star in one of those follow-ups. That’s not luck any more – that’s the universe telling us these things are all over the place!”

Their two new findings include a spider millisecond pulsar.

“The first was the detection of several millisecond pulsars (MSPs), particularly of the exotic ‘spider’ variety. A spider pulsar revolves around a companion star in such a tight orbit that it eats away at it, stripping and accreting matter from the unfortunate companion,” Smirnov said.

It was the first time that a millisecond pulsar like this one has been found in radio imaging data.

Smirnov said the team’s second find was a stellar radio flare. “While these stellar flares are not unprecedented,” he pointed out, “they are fairly elusive.”

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The star where the flare was observed is 1,300 parsecs away from Earth. A parsec is a measurement of distance equal to 3.26 light years, or about 206,265 times the distance between Earth and the sun.

“This particular star, at over 1,300 parsecs away, is no neighbour, so the flare must have been a particularly powerful event to be detectable.”

Smirnov said the team had seen this star before in one of its follow-up observations. “This reinforces the point that we should be seeing transients everywhere if we just get smarter at looking for them,” he added. DM

This story first appeared in our weekly Daily Maverick 168 newspaper, which is available countrywide for R35.

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