Intelligence: Alien Turret Contacts.
Make it possible to determine if, how many, and how big turret emplacements are on vessels. However, to be even to see them first, they need to be visible as if they were a ship of the same size at it's position. For instance, a resolution 20 sensor would see a 20 HS turret out to it's max range, but would need to be closer to see a 10 HS turret. The game, however, won't tell us what kind of turret, how fast it goes, or it's armor based on this info, just the size and quantity.
When a turret has a contact designated as a target however, if the turret is seen by active sensors, the active sensors will report the turret's tracking speed, up to the speed of it's target. For instance, if a 12,000 km/s turret is tracking a 6,000 km/s target, intelligence will report the "Estimate Tracking Speed" of the turret to be 6,000 km/s, until it tries tracking something faster.