Gravitational Wave Sky Localization: Detector Triangulation

LIGO's twin detectors and Virgo don't point at the sky like a telescope — they triangulate it. Because a gravitational wave crosses the Earth as a plane wavefront, the tiny light-travel-time delay between when it hits Hanford, Livingston and Virgo encodes the direction it came from. This simulator places the three real observatories on a 3D Earth, computes the actual time delays for any source direction you choose, and draws the ring of directions each detector pair's delay is consistent with — showing how three overlapping rings, fattened by timing uncertainty, narrow a gravitational-wave event down to a patch of sky small enough for telescopes to search for an electromagnetic counterpart.