A sudden, hugely powerful radio blast has been detected in a distant corner of the universe before falling almost instantly silent.
Scientists do not know what the cause of the "fast radio burst" was - and say they have only scant clues to help them decipher its origin.
But the eruption of the radio waves, lasting a fraction of a second, some 5.5 billion light years from Earth, is still hugely significant - mainly because researchers were able to find it in the first place.
The phenomenon of very short, very intense radio blasts was discovered only recently, after astronomers saw an unusual peak in data from the Parkes Radio Telescope in 2007.
Since then six more bursts have been discovered from the Parkes telescope, with a seventh discovered using the Arecibo telescope in Peurto Rico. But despite increasing numbers of the radio blasts, we still don't know what they are - and finding them as they happen, rather than afterwards, is incredibly difficult.
But now a team from Australia, led by Emily Petroff (Swinburne University of Technology), has found a way to look for the bursts in real time reports Phys.org.
Their study, published in the Monthly Notices of the Royal Astronomical Society, demonstrates how they were able to observe a "live" burst of radio waves using Parkes.
The burst they saw - exploding 5.5 billion years from Earth, and lasting just a few miliseconds - was detected quickly enough to tell other telescopes to point in the same direction and try to discover what caused it.
Astrophysicists at the University of Copenhagen did just that and found two sources of X-rays at that position. Those were observed from another telescope and found to be quasars - a type of pulsating black hole - which were "nothing to do with radio wave bursts, but just happen to be located in the same direction" said astrophysicist Giorgos Leloudas, Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen.
The issue for the team is that while they know how to look for the source of radio wave bursts, they don't have any idea about what that might be. Yet. What they know is that the light from the burst was polarised - meaning there is a magnetic field nearby.
"We found out what it wasn't," said Daniele Malesani, astrophysicist at the Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen:
"The burst could have hurled out as much energy in a few milliseconds as the Sun does in an entire day. But the fact that we did not see light in other wavelengths eliminates a number of astronomical phenomena that are associated with violent events such as gamma-ray bursts from exploding stars and supernovae, which were otherwise candidates for the burst."
"The theories are now that the radio wave burst might be linked to a very compact type of object - such as neutron stars or black holes and the bursts could be connected to collisions or 'star quakes'. Now we know more about what we should be looking for."