Vertex is the command and control center of the Heechee cloaking system and the focal poit of the energy fields produced by the Shield Generators. When it is activated, a series of on-board computers communicate with the generator and orchestrate the delicate ballet of forces necessary to warp space around the Assassin WatchTower.
It is located in the same system as the WatchTower, however the exact location was not in the Savant.