three starlights forming a triangular shape, slowly moving across night sky.

whilst observing constallations in the clear night sky, i noticed what looked to be three stars moving slowly in formation from a south-west to north east direction.
They looked like a right angled triangle, and only changed formation slightly as their light faded moving towards the north eastern sky.
 There were no flashing lights. They just looked like a constallation of three stars slowly traversing the sky.They did not wobble; there was no sound.I have seen many known phenomonon in the night sky,i have great knowledge of astromony, but have never experienced a sighting such as this.
We suspect the witness may have observed what are thought to be three U. S. Navy "NOSS" surveillance satellites.  PD