Galactic centre

Galactic Centre was a point used to measure other planets and locations. It was used as a starting point for galactic coordinates. For example, Gallifrey was located at 10-0-11-0-0 by 0-2 from galactic zero centre. (TV: Pyramids of Mars)

The Galactic Centre was also the centre of power for human affairs during the time of Helen A's rule on Terra Alpha. (TV: The Happiness Patrol)