[Ekaros]

It is in the name.

Unidentified "Flying" "Object". Anything that cannot be identified is classified unidentified. It is flying, and it looks like object. Someone records it and enters the data as trained.

Someone is paid to observe sky, they see something they can't explain, they log it as they are ordered or paid to do. It might be explained with further effort, or it is just artefact of some other phenomenon or activity.