Can you watch a gamma-ray burst from the side?

[Strato Incendus]

Since gamma-ray bursts travel at the speed of light, my state of knowledge is that, if one were to hit Earth, we would of course only see it the moment it hits us. Furthermore, to my knowledge, we haven’t observed any GRBs within the milky way yet.

However, what if there were a GRB within the milky way (i.e., much closer than the ones we’ve observed so far, in other galaxies) that wasn’t pointed at Earth, but instead, we were observing it from the side — could we watch it travel through space? For example, in order to see how far away it was from a solar system which it is going to hit at the end?

Since these bursts, as far as I know, last between a few seconds and one minute, I imagine the jet would already have “torn off” from its source. Meaning, there wouldn’t be an uninterrupted stream from the star / black hole that caused the burst all the way to the target. While the burst has already stopped at its source, its “point” should still be on its way. Basically, it should act like two arrows of light on their way, shot in opposite directions.

To my knowledge, gamma-ray bursts get wider the further they travel, like a cone shape. So the longer it travels, the easier it should be to see. Then again, the longer it travels, the further its energy should decrease, too — and, along with that, probably also its luminosity. Which in turn should then make it harder to see again.

So in short: With the telescopes on a spaceship, could you observe a gamma-ray burst from within the milky way from the side, in order to tell how far it is currently away from a planet it is going to hit in the future?

 

[jedishrfu]

Since it is light, you can't see it from the side unless it penetrates a cloud of particles, and scattering occurs. It's like a flashlight beam showing the dust in the air at night as you view it from the side.

https://www.shutterstock.com/video/clip-2607977-specks-dust-floating-beam-light

Recent telescope observations did spot a gamma-ray burst that was directed toward us.

https://www.scientificamerican.com/...urst-ever-recorded-rattled-earths-atmosphere/

A GRB this close means that astronomers can analyze the light they see from it in more ways than usual. Typically a burst’s light isn’t bright enough to clearly reveal details about the event that caused it. This specimen could help scientists better understand the central black hole engine that forms during a burst and the extraordinarily complex nature of the physics surrounding it.

It can also tell us about the Milky Way. The Swift observatory saw expanding rings of x-ray light centered on the GRB’s location, caused by dust clouds in the Milky Way located roughly 600 to 12,000 light-years from Earth. These “light echoes” happen when light hits dust clouds just off our line of sight to the GRB—so we see them to the side, next to the bright point in the sky. Because of the short amount of extra time it takes light from the blast to reach those dust clouds and be scattered toward us, we see rings of light moving outward from the center, their expansion rate related to their distance from us. Measuring these rings allowed astronomers to determine the distances to the clouds.

 

[Strato Incendus]

Sorry for my late reply, but thanks a lot for your answer! I’m not quite sure yet if I’ll actually have a GRB go off within the time frame of my story, or if it will just remain eternally in the background, as an allegory for the permanent threat of extinction, without anyone knowing when exactly it will be.

But if the GRB does go off at some point during my story, know I have a better idea how I could describe it — from the point of view of an observer on the sidelines.