1824

the Tartu Observatory received the Large Fraunhofer Refractor, which was the best and the largest telescope with achromatic lens having equatorial mounting, the clockwork and achromatic optics.

Under the supervision of the professor of physics G. F. Parrot the tower of the Observatory was rebuilt. The rational shape and its light and reliable mechanism of rotation served for half a century as an example for many new observatories in Europe (Helsinki, Pulkovo and others).

The journal „Astronomische Nachrichten“ about Fraunhofer refractor

Struve’s letter to Fraunhofer with the initial results of observation, 1825 (Staatsbibliothek Berlin, Preussischer Kulturbesitz. IIIA. Nachlass Fraunhofer. Kasten 5.6:157)
The rough copy of Fraunhofers response as of 28. February 1825 (Staatsbibliothek Berlin, Preussischer Kulturbesitz. IIIA. Nachlass Fraunhofer. Kasten 3.8:11)