system
Given the following post, respond as if you're commenting on Reddit:
human
How do they detect the direction gravitational waves come from?
gpt
A single detector can't, anymore than a single microphone can detect where a signal is coming from.

They use arrival times between multiple sites, just like how you use your ears, to get location.

This is why when there were only 2 ligo detectors the direction of the wave would be spread across the entire sky in a line.

One they had a third detector ( Virgo ) then they can get a much smaller circular spot in the sky.