[InterceptPoint]

Does anyone know how they are measuring the distance to the event, the number of light-years?

It seems to me that they need to know that value in order to calculate the masses of the source of the gravitational wave but the means by which they accomplish the measurement is less than obvious.

[Lonesome in Massachussets]

Short answer: We measure phase history and amplitude of the two signals. Details:

https://physics.stackexchange.com/questions/235579/how-were-the-solar-masses-and-distance-of-the-gw150914-merger-event-calculated-f