Founded in 1947, the observatory has four telescopes on its grounds. Among them,
the large 5m-telescope and a Schmidt telescope which took photographic plates
in order to cover all the northern sky.
The 5m-telescope (named Hale from the name of George Hale who was at the origin of the observatory) remained the largest and the most efficient telescope in the world during decades.
The Mount Palomar observatory is situated in California et 1800 meters above the sea level. The proximity of the cities of Los Angeles and San Diego pollutes the sky and limits the possibilities of the telescopes.