We were traveling along Yellowstone lake. I took a series of pictures of the snow covered mountains. When I down loaded the pictures into my computer, I noticed on one frame what appeared as a small object in the upper left corner. I thought it was a large bird so I started enlarging it. After the third enlargement, I realized it was no bird! I printed the object and it is in my pocession. I took a series of 3 pictures. In frame #1, it's not there. In frame #2, it's there. In frame #3 again, it's not there. It appears to be a cylinder shape with no wings, propellers, or motors that can be seen. Everone we've shown this picture including the local TV news station in Idaho Falls have said the same thing....It's a UFO. However, no body has contacted us on whether it's a real UFO. The original pictures are still in my computer.