Australian astronomers have discovered an object six to eight billion light years away that - in about a millisecond - ejected the same amount of energy that our sun releases in 2½ years.

And no one knows what it is.

Using a new $188 million CSIRO telescope that is not yet fully commissioned, Australian scientists detected a mysterious "fast radio burst" during a brief four-day pilot survey of the skies.

"January was our first commissioning run with no problems and bam! ... We saw it," said CSIRO astronomer Keith Bannister.

Fast radio bursts, or FRBs, are one of the unsolved mysteries of modern astronomy.

First detected at the Parkes radio telescope in 2007, there have only been a couple of dozen of these exotic objects discovered.

As their name suggests FRBs are extremely short bursts of radio waves from very far away indeed. What causes them is a topic of wild debate.

"There are more theories about what they are than the number detected," Dr Bannister said.

Dr Jean-Pierre Macquart from Curtin University, the co-author of the study, said it was unclear what FRBs are but that "the universe has more imagination than we do".

The bursts of radio waves are somewhat similar to that emitted by pulsars - the dense, rotating neutron star remnants of large stars. However, these lighthouses of the universe rotate with near atomic clock accuracy, sending a repeating signal out like a rapid metronome.

Fast radio bursts, however, appear to be one-off events - except for one example that emits radio waves with no discernible pattern.

While some have speculated these huge bursts of energy could be evidence of advanced alien civilisations, no one takes this particularly seriously.

So what does Dr Bannister think they are?

"I try not to have an opinion on this because you never know when the universe is prepared to make a fool of you," he said.

"It must be very different from the sorts of things we've seen before."

One theory is that FRBs are flares caused by magnetars - highly magnetised pulsars - interacting with some sort of debris or other objects, accounting for their one-off or irregular energy emissions.

Dr Evan Keane from Jodrell Bank radio observatory in Britain said there are possibly two types - young magnetars and perhaps neutron stars forming black holes.

Dr Bannister worked with Dr Macquart using the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in Western Australia to detect the FRB.

The discovery of "FRB 170107" after such a short survey means ASKAP is likely to emerge as the world leader in the hunt for fast radio bursts.

"It's the best instrument in the world to hunt for FRBs," Dr Bannister said, adding that since their discovery they have found two more FRBs using ASKAP.

The discovery happened using just eight of the telescope's 36 interconnected radio receivers. The fact it took just four days to find supports the idea that these events are common.

"We can expect to find one every two or three days when we use 12 dishes," Dr Bannister said.

Dr Macquart said the next step will be to determine more exactly where the FRBs are.

This study, published in The Astrophysical Journal Letters on Tuesday, narrowed the location of FRB 170107 down to an area of the sky about a tenth the size of a full moon.

"That's not accurate enough to determine what galaxy it came from," Dr Macquart said. "So we can't be sure how far away it is."

He said that the real strength of ASKAP was that it can provide data from 36 separate dishes, allowing for more accurate measurements of radio burst locations.

"This really puts us in the box seat. It's something that no other telescope in the world can do."

Dr Keane, who was not connected to the study, said that ASKAP should start to "rake in" FRB sightings once fully operational.

"I get my data from Parkes, which has a field of vision of 0.55 square degrees and that's seen as excellent. ASKAP has 160 square degrees of vision."

Associate Professor Tara Murphy at the University of Sydney, who was also not part of the study, said localisation of the FRB events is now vital.

"We can't really do a whole lot more science with FRBs until we know where they're coming from," she said.

She believes FRBs are extragalactic and might be connected with the exotic collapse of neutron stars and associated gamma ray bursts.

By localising FRBs, Associate Professor Murphy said optical telescopes will be able to examine their location.

She also said that now astronomers will be looking at the universe in gravitational waves, this will give us another tool with which to study them.