Telescopic dome
The round superstructure of the building, in which an astronomical telescope is set up for observation purposes, is called the observatory dome or telescope dome . Traditionally, the observatory buildings are cylindrical round structures and are covered with a rotating dome in the form of an exact hemisphere . The advantage of the dome shape is that the telescope can be moved freely inside both with the dome open and closed.
There is a closable opening in the dome, the dome gap, which usually extends from the horizon to the zenith . During the night, the movements of the dome and telescope must be coordinated to ensure that the telescope always has a clear view for observation.
Alternative designs
Although with the advent of the azimuthal mount in the late 80s of the 20th century, other designs than the dome, in which the telescope can also be moved freely, became common, the name was retained. The technical design of the dome has a direct influence on the quality of observation and can dramatically worsen the seeing if the ventilation is poor . Newer domes therefore not only have the observation slit, but also numerous controllable openings to ensure thermal stability and a smooth flow of air around the telescope. The shiny, light outer skin is supposed to reduce solar radiation during the day so that the interior can quickly adjust to the outside air temperature in the evening .
The sealing of observatory domes requires some effort. It usually works without any problems against precipitation, but not entirely against snow . For smaller or private observatories, instead of a dome, a sliding flat roof is usually more practical and cheaper.
For some of the giant telescopes (mirrors over 10 m in diameter) currently being planned, consideration is being given to dispensing with a protective structure: on the one hand to reduce construction costs, on the other hand because the movement of dome parts weighing tons means a lot of energy, waste heat and maintenance. Such solutions are only possible in arid regions such as the Atacama plateau in Chile .