The ID plates on the tower read "Republic Sienar Systems", meaning the Sienar observation module that made up the five story tower was erected prior to the end of the Galactic Republic. A second two-story building was constructed next to the module to contain offices. The tower itself was designed to be run by six droids, but by the Galactic Civil War this was reduced to one droid, J9-5, and two Human technicians.
- Galaxy Guide 7: Mos Eisley (First mentioned)
- Inside the Worlds of Star Wars Trilogy (As "Spaceport Traffic Control")
- Star Wars: Complete Locations (As "Spaceport Traffic Control")