Strange UFO snapped near Sofia, Bulgaria

On September 25, 2013, a person was near Sofia (in Bulgaria). He was playing with his phone and he has taken three photos of the sky. On one of this photo, it appeared a curious object, perhaps an alien spacecraft…

Witness statement:

On 25.09.2013 I was in the countryside near Sofia. So I was just playing with my phone taking pictures. I've decided to take image of blue sky with airplane passing over. At this moment nothing curious happened until few days after I began checking what I've made. I've made a sequence of 3 photos.

First one is taken at 10:05:27 and there is nothing interesting, second one at 10:05:29 which is only 2 seconds from the first one when the object is visible in front of the airplane  and third one is at 10:05:40 where is also nothing interesting.”

The coordinates are
Latitude = 42°57'56.1016"
Longitude = 23°24'42.6736"