Large circular UFO caught over American Fork

On May 31, 2015, an automobilist stopped near city of American Fork (Utah County, USA). He took photo of the landscapes where appeared a large and grey circular-shaped UFO. What is it?

Witness statement:

When driving up American fork canyon, stop to eat a tanking photos of the canyon as I was taking photo I got a photo of the mountain in the sky part of the photo there was a dark gray circle with a wright point on one side and it was in the control of the plane it was behind. In the other photos it is not there.