An observatory was a structure used for the study of astronomical phenomena. It was also a building in which people could study far away planets and stars without traveling into space.
In the 1970s, the Third Doctor and Davie Jenkins broke into an observatory to investigate a mysterious large object which had been detected at Downphilly, only to find it could not be detected by optical instruments. (COMIC: The Enemy from Nowhere)
Jodrell Bank Observatory detected the return of the planet Mondas to the solar system in 1986. Mount Palomar Observatory offered the first pictures of Mondas to International Television News. (TV: The Tenth Planet)
The same observatory traced the ATMOS signal to a Sontaran spacecraft. (TV: The Poison Sky)
The Eleventh Doctor consulted experts from Jodrell Bank during the Atraxi invasion. (TV: The Eleventh Hour)
In 2014, an observatory at Mount McKerry on the island of St Albans detected the approach of the Stormcrow and dealt with the No Things with the aid of the Fourth Doctor and Leela. (AUDIO: Night of the Stormcrow)
The Arecibo observatory in Puerto Rico was used by UNIT to track Nestene energy units. (AUDIO: Earthfall)
An observatory was one of the few surviving remnants of the Heavenite civilisation by the time of Bernice Summerfield's archaeology expedition on Heaven in the 26th century. (PROSE: Love and War)