Astronomers spot the brightest fast radio burst on record

A burst of radio energy from deep space just set a new record. It was brighter than anything like it ever seen before – and it came from a galaxy only 130 million light-years away. That’s unusually close by cosmic standards.

The burst, known as a fast radio burst or FRB, lasted just a few milliseconds but packed enough power to outshine entire galaxies in radio light.

This one was so intense, scientists gave it a nickname: RBFLOAT – short for “radio brightest flash of all time.”

What is a fast radio burst?

A fast radio burst is a short, intense spike of radio waves that lasts only a few milliseconds. That’s a thousandth of a second. But in that split second, it can outshine entire galaxies in the radio part of the spectrum.

FRBs have been baffling astronomers since they were first discovered in 2007. Nobody knows for sure what causes them. But this new detection could finally help change that.

Why RBFLOAT is a big deal

The burst was detected by an international team using a network of radio telescopes known as CHIME – short for Canadian Hydrogen Intensity Mapping Experiment – and a new system called the CHIME Outriggers.

The Outriggers, located at separate sites across North America, give the main CHIME telescope a powerful upgrade. Together, they allow astronomers to pinpoint exactly where a radio signal came from. This precision made all the difference.

On March 16, 2025, CHIME picked up an ultra-bright flash. It was so bright, in fact, that scientists weren’t sure if it was coming from deep space or just a burst of radio interference here on Earth.

But the CHIME Outriggers quickly narrowed it down: the signal came from a galaxy called NGC 4141, located in the constellation Ursa Major.

Where do the bursts come from?

The burst came from the outer edge of the galaxy – right near a region where new stars are being born. This area is hot, chaotic, and full of activity, which makes it a prime candidate for violent events like FRBs.

The current leading theory is that FRBs come from magnetars – a type of neutron star with insanely strong magnetic fields. These stars are known for producing powerful flares, especially when they’re young.

Because the burst came from just outside the star-forming region, it might have been produced by a magnetar that’s slightly older than most and had more time to develop.

“These are mostly hints,” said Kiyoshi Masui, associate professor of physics at MIT. “But the precise localization of this burst is letting us dive into the details of how old an FRB source could be.”

“If it were right in the middle, it would only be thousands of years old – very young for a star. This one, being on the edge, may have had a little more time to bake.”

New eyes on the sky

CHIME was originally built to map hydrogen in space. But over time, it became clear that the telescope was picking up something else: FRBs.

Since 2018, CHIME has detected about 4,000 fast radio bursts. However, until recently, it couldn’t tell exactly where the bursts were coming from.

That changed with the addition of the CHIME Outriggers – smaller versions of the telescope placed in different locations. When a flash is picked up, all of the telescopes work together to trace it back to a specific location in the sky.

“Imagine we are in New York and there’s a firefly in Florida that is bright for a thousandth of a second, which is usually how quick FRBs are,” said Shion Andrew, a graduate student at MIT’s Kavli Institute.

“Localizing an FRB to a specific part of its host galaxy is analogous to figuring out not just what tree the firefly came from, but which branch it’s sitting on.”

Diversity of fast radio bursts

Once they had locked in the location of RBFLOAT, scientists went back through six years of CHIME data to see if anything similar had been seen before in the same spot. Nothing was found. That puts RBFLOAT firmly in the “one-off” category – a burst that flares once and then goes silent.

“Right now we’re in the middle of this story of whether repeating and nonrepeating FRBs are different. These observations are putting together bits and pieces of the puzzle,” said Masui.

That’s a major question in FRB science: are the ones that repeat caused by something different than the one-time flashes? This discovery doesn’t answer that question – but it gives researchers a big piece of evidence to work with.

Because it’s so bright and close, they can study the area around the burst in greater detail than ever before.

“There’s evidence to suggest that not all FRB progenitors are the same,” said Andrew. “We’re on track to localize hundreds of FRBs every year. The hope is that a larger sample of FRBs localized to their host environments can help reveal the full diversity of these populations.”

The race to understand FRBs

For now, scientists are digging deeper into the data – studying not just the burst itself, but also its environment, its galaxy, and any signs of activity that might hint at what caused it.

The discovery of RBFLOAT doesn’t solve the FRB mystery, but it’s one of the clearest clues yet.

The more fast radio bursts that scientists find and locate, the closer they’ll get to cracking the code. And with CHIME and its new Outriggers up and running, the race is on.

The full study was published in the journal The Astrophysical Journal Letters.

Image Credit: Danielle Futselaar

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