Just spotted this UFO hovering nearby. It emitted a cyclic pulse of bright light, which I suspect was some sort of communication.
Or, it was a balloon of some sort and was reflecting the afternoon sun.
Update: It seems there was a similar sighting in Arizona, which turned out to be a NASA gamma-ray-measuring balloon. (via UPI)
Update 2: This report was duely logged by the Alien, UFO and Paranormal Times and Alien Casebook.