Onsala Space Observatory was created in 1949.
Onsala's population is 11,951.
The area of Onsala is 10.53 square kilometers.
Onsala's population density is 1,135 people per square kilometer.
It is not an observatory, it simply is an instrument (= a telescope) flying in space, orbiting Earth once in 97 minutes. It is operated from the ground and the "observatory facilities" are on the ground.
Although often called the Montreal Earth Observatory, the space observatory is owned and operated by NASA. The observatory is at the Goddard Space Flight Center in Greenbelt, Maryland.
Modra Observatory was created in 1988.
Stellafane Observatory was created in 1924.
Erbil Observatory was created in 1973.
Steward Observatory was created in 1916.
Bosscha Observatory was created in 1923.
Mead Observatory was created in 2001.
Goodsell Observatory was created in 1886.