NASA astronomers were blown away last week by what was far and away the strongest gamma-ray burst (GRB) ever observed. GRB 080319B, shown here in x-ray [left] and optical/ultraviolet [right] views captured by the Swift satellite, burned so brightly that its afterglow was briefly visible to the naked eye from its origin 7.5 billion light-years (or half a universe) away. If placed side-by-side with the brightest supernova ever seen, the burst would still outshine it by a factor of 2.5 million, researchers calculated. GRBs typically occur when the explosion of a dying star gets channeled into twin high-speed jets. Astronomers are mystified why this one shined so intensely. The burst may simply have been extra powerful or its very narrow jets may have pointed directly at Earth.
More photos of this event and other interesting stuff here.
The reports I've read about this GRB state that it was visible because one of the jets pointed directly at us, but also that was is visible in a GRB is the afterglow produced when the jets of gamma rays energise surrounding gas.
This to me implies that the afterglow only emits visible light in the same direction as the jets. Otherwise, we would visibly see many more GRBs, but not detect the gamma rays because they weren't directed at us.
Is it true that the light in the afterglow is only emitted in the same direction as the jets from the collapsing star? Or am I missing something..