Nearly Invisible and silent UFO outline hovering slowly, Arch shaped.

Tonight was a clear and beautiful night, no clouds in the sky that I could see. I was observing a white dot in the sky, looked like a satellite moving slowly East and caught my attention. It wasn’t blinking, and looked very far away. No big deal to me, as I live by the Air Force base and witness lights and planes in the sky all the time. It was at night in the city by downtown, so the sky was dark, but it also had a very soft light glow. As I was continuing to watch the sky for a minute, I then noticed what looked like the faint edge of a craft almost directly in front and above me. It seemed almost invisible- and I can’t explain much of the exterior other than that. I thought it was a group of birds possibly flying in a line up high. When I looked closely, it was the edge of something very large, and flat. It had no lights. The strange thing was that it was moving very slowly and to the East. No abrupt flight patterns, but maybe a steady 200mph . It continu! ed hovering over buildings, and I lost sight. It was by far the strangest thing I have ever seen. I see military planes flying all the time, and this was something large. It made no noise, and was just moving slowly above.