The mysterious "Wow!" signal from deep space, caused by a yet unknown astronomical event, was much stronger than previously thought, a new study suggests.

"Wow!" is the name given to the enigmatic and powerful radio waves recorded by astronomer Jerry R Ehman in August 1977, and has long been held to be the most promising "alien" signal ever detected from space.

It received the moniker as scientists who first recorded it were so astonished they wrote "Wow!" next to the signal on a printout, and the name has stuck ever since.

For long, both the source and meaning of the signals have been widely debated in the scientific community.

Now, a long list of researchers, including astronomers and volunteers, have provided corrections and fresh insights into the signal and its potential causes.

New analysis of the signal's original data could explain why the enigmatic radio waves have been difficult to identify, they say.

"The Wow! Signal, detected in 1977 by the Ohio State University SETI project, remains one of the most intriguing unexplained radio transients," researchers write in a yet-to-be peer-reviewed study.

The latest findings were made thanks to the efforts of volunteers who ran more than 75,000 pages of signal's original data through an optical character recognition system, overseen by human validators.

This allowed an in-depth computer analysis of the original signal for the first time, researchers say.

Scientists could now narrow down the part of the sky the signal could have come from, along with improved certainty of its location by two-thirds.

The latest estimate of the signal's strength also suggests it is significantly higher than previous calculations.

Researchers also corrected what was likely a mistake in the calculation of the signal's frequency, indicating the source of the signal was likely spinning much more rapidly to create the kind of radio waves.

The findings completely rule out the possibility that the signal was human-made as there were no known TV stations or satellites at that time, which could have caused these types of waves.

An internal software error also didn't contribute to the strange signal, scientists said.

This confirms the signal is astronomical, but does not mean it is of extraterrestrial origin, they noted.

"Our analysis provides additional support for the hypothesis that the Wow! Signal most likely had an astrophysical origin rather than being attributed to radio interference," researchers wrote.

"These findings provide the most precise constraints to date on the location, intensity, and frequency of the Wow! Signal and offer a new path to identify its origin," they said, adding that the phenomenon "requires further investigation".

Mysterious 'Wow!' signal from space was much stronger than thought, scientists say