The picture below shows a Kuiper Belt object and a number of stars. It was recently taken by the New Horizons probe and published by NASA.
The arrow points at the KBO and the rest of the bright points visible are stars.
In the top-left corner, there's an artefact that looks like a secondary mirror of a telescope. This is common in reflectors when looking at an object that is out of focus.
My question is... what could it be that New Horizons captured that was close enough to produce this out-of-focus image? It seems we're looking at a small light source that, compared to the KPO and obviously the star field, is relatively close to the objective.