Galactic coordinates
Gallifrey was located in the constellation of Kasterborous, at galactic coordinates 10-0-11-0-0/0-2 from Galactic Zero Centre. (TV: Pyramids of Mars, Full Circle, Death in Heaven)
The Ogron planet was located on the outer extremity of the Mutter's Spiral (PROSE: The Romance of Crime) at galactic coordinates 0110011 by C2 (PROSE: Interference - Book One) or at 2349 to 6784. (TV: Frontier in Space)
The thirteenth moon of the thirteenth planet of the Thirteenth Galaxy was located in galactic coordinates: 13:13:13:13:13:13. (COMIC: Triskaidekaphobia)
Attempting to identify a Pyrovile, the Tenth Doctor asked it for its galactic coordinates. (TV: The Fires of Pompeii)