GW150914 - two black holes merge and the signal reaches Earth

node

The two Advanced LIGO interferometers registered a coincident signal sweeping upward in frequency over about a fifth of a second and then cutting off - the inspiral, merger and ringdown of two black holes of roughly thirty-six and twenty-nine solar masses, forming a final hole of about sixty-two and radiating some three solar masses as gravitational waves. The signal arrived at Livingston about seven milliseconds before Hanford. It was the first direct detection of gravitational waves and the first observation of a binary black hole system of any kind; the source lay several hundred megaparsecs away, and the event happened before the detectors' formal observing run had officially begun.

A node is not a place. Drawing it on a map would assert something about the world that no stored fact supports.