Possible flying saucer caught over Newcastle, WY

On May 19, 2016, a UFO flying at high altitude was caught over Newcastle, Wyoming. Witness didn't notice until he looks at the pictures. What is it?

Witness report:

While out filming wildlife, I stopped and took two photos of a hawk. the two photos are only a few seconds apart, the object is only in one photo. i did not see the object until i looked at the pictures i had taken, which unfortunately was over a year later.in the second photo, where the hawk is looking to the side, about beak level and to the right you will see the object.