Man, this topic is back? Wow.
About the ST sensors. I have observed that Star Wars seems to have very detailed sensors in some of the books and movies, i.e. the Executor being able to determine the existence of a small shield on Hoth outside the system, and yet be completely opposite in other works, (How could you not see the Death Star wasn't a moon?) I think the whole sensor thing is more or less the fault of the writers rather than the universe.