Tour 1: The great refractor at the Department of Astrophysics

(Faculty of Earth Sciences, Geography and Astronomy of the University of Vienna)

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The observatory of the University of Vienna was built 1874-1879. Similarly to the observatory in Berlin, it was designed in the shape of a cross. Even today, it presents the largest observatory building in Europe (73 m in width and 101 m in length). On June 5, 1883, it was ceremoniously opened in the presence of Emperor Franz Joseph I.

The building hosts the large 68 cm Grubb Refractor located in the center of the observatory (the large dome measures 14 m in diameter). At the time of its completion, it was the largest refracting telescope in the world. With its length of 10.5 m it has a total weight of 13.5 t, in addition, the moving part weighs up 5.5 tons. In order to simplify observations and make them possible also at near horizon levels, the dome was electrified in the 1950s and a lifting platform was added. It is impressive to experience the lifting of the entire platform and the rotation of the dome. To avoid light-smog from the city, the observatory was built on a small hill. If the weather is fine you will have a great view over Vienna. It is interesting to mention that the refractor is still in use for scientific investigations due to the CCD detector technology.

Besides the refractors, you will visit the remarkable Library of the Institute of Astronomy. It hosts 5 books older than 1500. In addition, 56 books were printed before 1600, and a total of 500 were printed prior to 1800.

The building hosts a small museum with an impressing collection of historic books and instruments (telescopes, spectrometers, globes, clocks, and other astronomical instruments) documenting the history of astronomy in Vienna. Currently the observatory-museum is under reconstruction. However, already the architecture of the building is worth visiting. Coming from the park area surrounding the observatory located in the western part of Vienna, you will enter the building. The base of the refractor is reached via an imperial staircase.

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