Astral map

The Doctor owned in his first incarnation an astral map which recorded the astronomical location of various stars and planets. Upon arriving at the planet Vortis, the Doctor was forced to use the map by the Animus in order to discover the plans of the invading Menoptera. (TV: The Web Planet)

The First Doctor later used the map again when the Drahvins allowed he and Steven Taylor to go back to the TARDIS to find out how many days before the planet they were on exploded. The Doctor discovered it was not a fortnight, but merely two days before it exploded. (TV: Galaxy 4)