However, in quasars and other violently active extragalactic sources, explosive events in which 1051 ergs of high-energy particles are released on a time scale of months are commonly observed.

On the other hand, VHE observations of extragalactic sources set upper limits to the EBL.

"That would have to be an extragalactic source, and the macroscope doesn't reach - " Ivo shrugged.

"It's rather farfetched," Stone said, "to postulate debris from some extragalactic source other than--" "I agree," Leavitt said.

It achieved the first definitive observation of high-energy cosmic gamma rays from both galactic and extragalactic sources.

His team showed in 1997 that gamma-ray bursts came from extragalactic sources, and identified optical counterparts.

Because of the widespread interest in interstellar formaldehyde it has recently been extensively studied, yielding new extragalactic sources.

Although relativity implies that there is no true inertial frame, the extragalactic sources used to define the ICRF are so far away that any angular motion is essentially zero.

Especially static from extragalactic sources.

Martin et al. made the first spectral line survey towards an extragalactic source, targeting the starburst galaxy NGC253 across the frequency range 129.1-175.2 GHz.