The first and most important method was the same one the Event Horizon Telescope uses today—connecting multiple geographically distant radio telescopes to form an interferometer, which adds together waves collected at different telescopes to produce a new, stronger wave. In the early 1960s, almost as soon as the National Radio Astronomy Observatory in Green Bank, West Virginia, was completed, astronomers started pointing its two-station interferometer at the galactic center. Then in 1966, observing relatively low-frequency radio waves, astronomers there detected the first signs of what we now know as Sagittarius A*. The resolution was far too low to yield a definitive observation, but eight years later, Green Bank astronomers using an upgraded interferometer capable of capturing higher-frequency waves proved that something extremely dense and bright existed at the center of the galaxy. Something was sitting at the core like a gyroscope, hovering in place while the rest of the Milky Way churned around it. Eight years later, one of the astronomers named the object—which, when viewed from Earth, appears to lie in the constellation Sagittarius—Sagittarius A*.