Mysterious white light snapped over Cancun

On January 17, 2015, a man and his wife that were on vacation in Cancun (Mexico) have photographed a mysterious circular-shaped UFO in broad daylight. What is it?

Witness statement:

My wife and I are vacationing in Cancun, Mexico and observed a small rainbow broken between both sides of the sun. I took two photographs and never thought twice about it until reviewing the day's activities with my wife back at the hotel. We noticed two "white light" anomalies in the picture that neither of us saw when taking the pictures. I had put on sunglasses to get a better view of the rainbow and only saw the sun, rainbow and clouds. I did, however, take note not to capture any planes flying over as to not ruin the picture if it turned out good. The Cancun airport is nearby and a plane will fly in the near vicinity from time to time. It is clear to us that no plane was in the shot because we listened and looked before taking the pics. Both were taken while I was lying down on the poolside chase-lounge and couldn't have been more than 5-10 seconds apart. I'm attaching the photos and you can see the information in the file shows they were both taken at 1:39pm today. This is more a "for your information" than anything else. Not much more of a story attached to it and these may not be anything at all but we thought they were interesting. Thank you.

Kevin & Nancy Coleman