Kasterborous

Kasterborous (Cas-TER-bor-os) is the constellation in which the planet Gallifrey was located. (DW: Pyramids of Mars) When explaining where he was from, the Doctor liked to include that Gallifrey was located in Kasterborous. (DW: Attack of the Cybermen, Voyage of the Damned)

Behind the scenes

 * It has been suggested that the design on the back of the TARDIS key (as worn by the Third Doctor, Fourth and Eighth Doctors) is a representation of the constellation, with Gallifrey's twin suns being the central star in the pattern.
 * In the revived series, the name Kasterborous was first mentioned in DW: Voyage of the Damned.