One object--thought was satelite. Flying high alt. (satelite area) E to W Extreme speed- Brilliant light flash of 1 sec duration another 5-6 sec later of same duration-then vanished.There was one object that we thought was a satelite. We were looking for satelites so it was flying at a high alttitude in the area we had already seen satelites in. It was traveling roughly E to W at extreme speed-crossing the sky in just a few seconds. From the object came a brilliant light flash of 1 sec duration and another 5-6 seconds later of the same duration-then the object completely vanished 10-15 degrees before reaching the horizon. Three observers--husband and wife both professionals and another professional (all in education).