Vela Incident is located in 100x100

The Vela Incident — sometimes referred to as the South Atlantic Flash — was an unidentified "double flash" of light that was detected by an American Vela Hotel satellite on September 22, 1979 near the Prince Edward Islands or Antarctica. There is uncertainty as to the true nature of the flash though it is widely believed to have been the result of a nuclear detonation.

• http://en.wikipedia.org/wiki/Vela Incident