Kasterborous
From Tardis Wiki, the free Doctor Who reference
Kasterborous is the constellation that the planet Gallifrey was located. (DW: Pyramids of Mars)
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 sun being the central star in the pattern.
