I saw it too (it was around 6:20), and nearly posted about it. It was on a south-north trajectory, pretty low and I noticed it was pretty much going along at the same altitude before it disappeared. Given I live near DCA, my first thought was, "This is not a regular airplane out of DCA", then I thought maybe the rocket launch at Wallops had happened and it was flying awfully low (the launch was the night before, and yes, I realize a rocket flying that low would be a problem), followed by thinking it was maybe a fighter jet on full afterburner, although there was no noise like you said. It was that bright.