pendragonman
Absent Friends Margrave
Not only is that not true (A missile-armed ship would be able to fire at a ship in the sensor shadow of a planet using relayed sensor data), it's also a false premise. A freighter that jumps into the system at the jump limit isn't going to enter any sensor shadow until it reaches the planet itself. Hopefully you don't propose that a pirate would attempt to intercept a ship in orbit around the planet? Well within the 10 diameter limit, which means that if the ship tries to jump, odds are that it will remove itself from the population of active pirate ships without any help from anyone.
If the merchie jumps in at the 100 d limit on the opposite side of the planet, he darn well is in the picket's sensor shadow of the planet. Yes, planetary repeaters could move that data to the ship, but now you are subjecting the system to larger error computations.
Yes, a missile sent on a ballistic trajectory to a target in the sensor shadow could be fired using the relayed data. This would also make it much simpler to intercept as I said in my original arguments. That is a huge flight time for the missile.
While I wouldn't recommend jumping from 5 diameters (the boom factor is huge), I certainly would try from 10 or 11, especially if I have a good black gang.