Telescopic column
As a telescopic column or telescopic pillars a heavy metal column or a brick is pillar as a solid foundation for a heavy Fernrohrmontierung referred.
While a solid tripod is sufficient for small telescopes weighing up to around 15 kg , a more stable set-up is required for larger instruments - especially in professional observatories or public observatories . However, you also need appropriate structural measures, such. B. a massive vibration-damped concrete ceiling on the upper floor of a building or a foundation that is deeply embedded in the ground .
Private observatories
For a well-equipped private observatory and an equatorially mounted telescope of 100 kg, for example - which corresponds to a lens telescope with an aperture of about 20 cm or a reflector telescope of 30-35 cm - a column with a diameter of about 15 cm and a foundation at least 60 cm deep ( frost line ) required. The weight could also be supported by a thinner column, but the vibrations would be noticeable. The column is often set in concrete in a sewer pipe up to 30 cm thick . Concrete rings with a diameter of 1 meter are also suitable as a foundation for even heavier instruments.
Professional observatories
The telescopes weighing tons in even larger observatories require a pillar that is several meters deep in the rock, which is mechanically isolated from the surrounding building in order not to transmit any vibrations to the telescope. For example, the double astrograph of the Vienna University Observatory, built around 1880, rests on an approximately 10 meter high pillar with a 3-4 meter deep foundation. The large refractor 68/1050 cm, on the other hand, whose main dome lies at a height of 27-36 m, rests on a 35 m high pillar, the lower 5 m of which is set in rock. At its base it is almost 10 m in diameter. Its bricks, which are ventilated in the basement of the building, guarantee even temperature control without any rotation of the pillars .
With the largest lens telescope in the world (102 cm / 20 m) at the Yerkes Observatory , it was decided in 1895 to erect the top 10 meters of the pillar in the huge dome using a hollow construction. This had already proven itself in 1879 in the Nice observatory .
With modern giant telescopes with mirrors ten or more meters in diameter, which instead of a high dome usually have a cube-shaped protective building on the ground, a column is not necessary. The foundation extends deeper into the natural rock, but protrudes only a little above ground level.
literature
- S. and P. Friedrich: Handbuch Astronomie , chapter mountings; Oculum-Verlag 2015
- Jürgen Hamel , Thomas Posch : The history of the Vienna University Observatory , p. 223 ff., Harri-Deutsch publishing house, Frankfurt 2010
Remarks
- ↑ z. B. Klauser observatory, Puchenstuben (Lower Austria)