Figure 2: The 1.23 m telescope of Calar Alto. (a) The drawing shows the mechanics and the hydraulic system of the 1.23 m telescope of Calar Alto. One of the mechanical peculiarities of the telescope is the presence of a steel sphere (indicated by a red arrow) which, by means of a high-pressure hydraulic system, supports all the weight of the telescope. (b) Picture of the 1.23 m inside the dome. As seen, the instrumentation is always located in the Cassegrain focus. Note the German mount of the telescope.