A starfish like disc caught over Tucson, Arizona

On December 18, 2016, a dweller of Tucson, Arizona, was in his back yard. By looking at the sky, he saw a metallic rotating disc-shaped UFO. It reflected the sun. What is it?

Witness statement:

I was out in my back yard doing yard work at about 11:30am on 12/18/16. A reflection from the west at approximately 5-10 thousand feet caught my attention. When I focused on it, I could see that there was something that was metallic and rotating clockwise in a slow, stable, and consistent manner. There was no noise at all. I had my phone and tried to take a picture, but the object was too high up for me to get a good shot. I ran inside and got my SLR camera, quickly changed lenses to my telephoto lens, and ran back outside, thinking that the object might be gone by this point. It was still there, so I started taking pictures. The object appeared and then disappeared from my view based upon how it was reflecting the sunlight. Since it seemed to be several miles away, I had a hard time focusing my camera on it, but I was able to get several good shot. After around 15 minutes, I was no longer able to find it in my viewfinder or by simply looking in that direction. I got the impression that it exited my view following a consistent NW path until it left my field of vision. The only thing that was left in the sky was a jet heading from the W to E at approximately the same height (this is an estimate from my vantage point, and I am not an expert so couldn't say for certain). I also took pictures of the jet for comparative reference.