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48-inch reflecting telescope of the Carl Zeiss Jena company

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48-inch (122-centimeter) telescope of the Carl Zeiss company is the oldest telescope of the Crimean Observatory. The control system of the telescope is currently being modernized.

Primary mirror diameter1.22 m
Focal length8.4 m
Optical systemsCassegrain focus (f/20)
Equipment
Coordinates44°43′37″ N;  34°00′56″ E

48-inch (122-centimeter) telescope was manufactured by the German company Carl Zeiss for the Berlin-Babelsberg Observatory in the early XX century. It was the fourth reflecting telescope manufactured at the optical workshops of the Carl Zeiss company. 48-inch telescope was installed on the original parallactic mounting equipped with a counterweight system for unloading the telescope and rotation axes. A characteristic feature of this design was applying hollow axles, durable rods and counterweights. Metal rods bore the telescope and counterweights, while the load on the bearing axes of the telescope had been greatly reduced. Due to such a design, it was possible to achieve a very precise and frictionless movement. This original mounting was developed by the director of the design-engineering department of the Carl Zeiss company engineer Franz Meyer (1868-1933).

Unfortunately, because of the World War I and global crisis after it, the 48-inch telescope was not operated until 1924. Starting from this time, Babelsberg Observatory became the most technically equipped observatory in Europe. The 48-inch reflecting telescope has remained the largest in Europe for 20 years (from 1924 to 1944). The development of the photoelectric method for studying variable stars and spectroscopic observations with the 48-inch telescope made the Babelsberg observatory well-known throughout the world.

This magnificent telescope was used by such well-known German astronomers as prof. Paul Gutnik, prof. Richard Prager and prof. Herbert Schneller. Three craters on the Moon are named after these prominent German scientists.

A variety of researches were carried out at the 48-inch reflector in the period from 1924 to 1944. In particular, thousands of photographs for several dozen of the most interesting variable stars were taken, color indices of Jupiter’s and Uranus’ moons were measured, several globular star clusters were studied detecting tens of variable stars in it.

The simultaneous photometric and spectroscopic observations of various astrophysical objects have been carried out at the 48-inch telescope since 1929. There were organized long-term studies of early B- and A-type stars with variable radial velocities aiming full identification of all spectral lines. The nature of unusual Wolf-Rayet-type stars was studied, as well as origin of interstellar calcium lines and law of interstellar absorption. The orbital elements of two dozen eclipsing binary and spectroscopic binary systems were detected and atlases of spectral lines of several novae and supernovae developed.

After the World War II the telescope was transported from the Babelsberg Observatory to the Crimean Astrophysical Observatory, instead of destroyed 1-m telescope of the Simeiz Observatory. At the 48-inch telescope under the guidance of prof. Mustel a new generation of Soviet astrophysicists-spectroscopists has grown up, among them - the future president of the International Astronomical Union A.A. Boyarchuk and Director of SAO I.M. Kopylov with the largest at that time 6-meter telescope.

The system of two-dimension spectral classification of hot stars was developed, stars with emission lines were studied, the first evidences of thermonuclear reactions in stellar interiors were detected, and analysis of the chemical composition of stellar atmospheres was carried out. Prof. N.A. Kozyrev discovered the signs of volcanic activity on the lunar surface.

The Crimean Astrophysical Observatory has started active cooperation with the Main Astronomical Observatory of Ukraine since 1996. The two-channel high- speed photometer was mounted on the telescope, it was used for observations of non-stationary active stars and galaxies. Within the framework of this project, the 48-inch telescope was included into the International Synchronous Network of Telescopes located in several observatories of Europe, namely, in Bulgaria, Greece and Russia.

In 2011, in the frame of the joint project between MAO NASU and CrAO the reconstruction of the telescope was started with the aim of its returning to the number of active astronomical instruments. The ultimate goal of modernization is complete replacement of the obsolete electromechanical parts of the telescope and installation of the system of the automatic remote control from the remote control panel.

By now sensors of the precise angular orientation of the telescope have been installed, kinematic and wiring diagrams of the telescope developed, mounting and adjustment of the electrical equipment to ensure fast movement of the telescope performed, repair of the telescope dome completed. As a result of full implementation of this project, the 48-inch telescope is to be included into the number of automated astronomical instruments intended for solving up-to-date astrophysical problems of modern astronomy.