On January 23, 2013, in the southern area of Costa Rica, where UFO sightings are reported on a regular basis, a Costa Rican pilot was filming a turn of his aircraft with his smartphone when a fast-moving, circulate object zipped across the sky in front of him. Pilot Joseph Daniel Araya has logged more than 500 hours. Astronomer Jose Alberto Villalobos examined the footage and estimated that the object could have a length between 7 and 10 meters in diameter moving at a speed of 3600 kilometers per hour.
We could be looking at lens reflection here but the video in interesting on three points: (1) although the airplane turn is smooth and the camera appears to have been held steady, the full-length video shows the object speed accelerating and decelerating, (2) there is not much light flare (as would be expected) around the object, (3) there are other videos from the same area showing objects with the same characteristics as the one Araya filmed.
The video below was taken from a local Costa Rican broadcast and includes the original audio.