# Relativity of simultaneity - An example

Your logic is correct but for one misunderstanding right at the beginning. The observer is smart enough to know that just because the photons are *received* simultaneously doesn't mean they were *emitted* at the same time. The emitting of a photon and the receiving at a different time and different place are *two distinct events*, as explored further in this post, among others.

Basically, you need to find a position *and* a velocity such that the observer *infers* that the photons were *emitted* simultaneously. The observer makes this inference by saying the travel time for a photon is the distance between his current position and the source, *as measured in his moving frame*, divided by $c$.

In fact, you don't even need to solve for the position to get the velocity, but I'll let you crank through the appropriate Lorentz transformations.