Unseen UFO Appears In One of Two Photographs Taken Less Than 5 Seconds Apart

I was facing west and watching the sunset in a parking lot across the street from the downtown municipal airport. There were no planes on the ground or in the air. There were no birds flying and no wind. There was no sound of any kind other than birds chirping in the trees.
 I shot two pictures less than five seconds apart with my cell phone camera. I did not see or hear anything in the sky. The second witness with me quickly noticed an object in one of the pictures which we could not identify. Neither one of us saw the object in the sky or heard it come or go, but it appeared in one of two photographs taken less than 5 seconds apart.
 The object in the photograph is completely black with no lights of any kind and it has an irregular elongated shape.