The observatory

Observatory technology

The centerpiece of our observatory is a Schmidt-Cassegrain reflector telescope with a mirror diameter of 35.6 cm (14″) and a focal length of 3910 mm (manufacturer Celestron, designation C14).

Reflecting telescopes have imaging errors that cause blurring and distortion, especially at the edges of the image. They are only of limited use for astrophotography. With the Schmidt plate, these peripheral imaging errors of the mirror are corrected so that the image is sharp and distortion-free right up to the edge of the image. The design principle was first used for astro cameras, which are also known as Schmidt cameras. Celestron has also used this system for amateur telescopes, which are therefore also suitable for photography. 

The magnification depends on the eyepieces used. We use eyepieces with a focal length of 40 mm to 10 mm, which give magnifications of 98 to 391. The resolving power of a telescope is primarily determined by the aperture, but also by fluctuations in the atmosphere. Astronomers call the latter "seeing".

For solar observations, the telescope aperture is covered with a solar filter. This reduces the intensity falling into the telescope by a factor of 100,000 and therefore protects the mechanics and the adhesions of the optics, but above all the observer's eyes. For solar observations, we also use another telescope specially made for observing the sun. It has an aperture of 40 mm and a focal length of 400 mm. An H-alpha filter is permanently installed, which only allows light in a narrow wavelength range to pass through. The sun appears in red light and ejections of matter (prominences) can be seen at the edge of the sun. 

There is also a 900 mm refractor for observing larger areas of the sky and open star clusters such as the Pleiades.

All the instruments are mounted on a plate and are moved by a special mount that follows the movement of the celestial objects under computer control.

The club also has two All Sky cameras. The "All Sky 7" consists of seven individual cameras under a protective acrylic glass and is part of the "European All Sky7 Fireball Network". The network is in operation around the clock and the current images from many AllSky cameras at various locations, including the one in Zweibrücken, can be viewed at

can be retrieved. They record the tracers of meteors (shooting stars), which are produced by meteoroids (mostly dust grains and millimeter-sized rock or metal particles) that enter the Earth's atmosphere from space at speeds of up to around 70 km/s. Larger particles (> around 10 mm) produce impressive tracers and are known as fireballs or bolides. Larger particles (> about 10 mm) produce impressive trails of light and are referred to as fireballs, fireballs or bolides.