When LIGO, the Laser Interferometer Gravitational-Wave Observatory, and its European counterpart, Virgo, detect a gravitational ripple from space, a public alert is sent out. That alert lets researchers know with a decently high confidence that this ripple was probably caused by an exceptional cosmic event, such as the collision of neutron stars or the merging of black holes, somewhere in the universe. Then starts the scramble. A pair of researchers is assigned to the incoming event, analyzing the data to get a preliminary location in the sky whence the ripple…
