Ústecká hvězdárna

From Jan Mayen to the Klementinum

The observatory's crown jewel was a broken transit instrument by Pistor & Martins with a 68 mm objective, adapted for the Horrebow–Talcott method of measuring stellar meridian crossings. This was no ordinary piece of laboratory equipment: it had been carried to the Arctic during the 1882–1883 Austrian polar expedition to Jan Mayen. In 1931, additional instruments were transferred from the historic Klementinum Observatory in Prague, further enriching the station's capabilities.↗↗

Beyond astronomy, the site became a hub for geophysics. In 1930, a cellar was built about 40–50 metres north of the main building—constructed without a single iron nail—to house a variometer for measuring magnetic declination. Coal mining companies contributed to the cost because precise magnetic data was essential for underground surveying. During World War II, the German Mining School in Duchcov continued magnetic measurements here for the same practical purpose.↗↗

The Einstein connection is indirect but real. After the sudden death of observer Rudolf Tschilschke in 1933, Erwin Finlay-Freundlich—Einstein's longtime collaborator and briefly a professor at Charles University—took charge. Arriving in Prague from Istanbul in 1937, Freundlich suspended the magnetic and meteorological observations but later reinstated weather readings at the request of the Czechoslovak State Meteorological Institute. The station also served as a meteorological complement to the well-known Milešovka observatory on the peak directly opposite.↗

Decline and Rediscovery

When the German University was dissolved in 1945 by presidential decree, its scientific assets passed to Charles University. Professor Guth and docent František Link hauled the instruments—reportedly some smuggled across the border under straw on a horse cart—to the Ondřejov Observatory. The Liboňov building itself changed hands repeatedly: state forests, then recreational use, then civil defence, then private families who treated it as a mountain cabin. By the 1970s it was left to collapse. Amateur astronomers in Ústí nad Labem considered restoring it in 1977 but never gained access. For decades, only the outline of foundations in the forest remained.↗

In January 2022, entrepreneur Vít Musílek and his wife Viky Yang purchased the plot. Over six months of archival research, they located the original construction plans and even tracked down the period Steinheil telescope, which survives at Ondřejov. Their vision is full restoration to the 1929 state, opening the site for public stargazing, education, and university research.↗

Today's Projects

The restoration is not just nostalgia. The registered association Ústecká hvězdárna is developing several active programmes at the site. The 1930 magnetic cellar is being revived as a node in a modern seismological network. In late 2024, the first major project since the 79-year hiatus took flight: PRIM Kosmos watches—made by Czech horological company ELTON—were launched to the stratosphere, reaching 31 km altitude, surviving temperatures of −70 °C and speeds of 286 km/h to become the first Czech-made mechanical watches in the stratosphere. The charitable auction that followed helped fund the observatory's revival.↗↗

The association also maintains a wildlife observation hide near the site, inviting visitors to experience the quiet of the forest and a genuinely dark night sky free from light pollution—echoing exactly why this hillside was chosen nearly a century ago.↗

Visiting the Site

The observatory lies in Liboňov, a small village that is part of the municipality of Telnice, roughly 11 km east of Ústí nad Labem in the Ústecký region. The setting is on a forested south-facing slope of the Ore Mountains; the scenic Elbe Sandstone Rocks (Tiské stěny) are nearby. The site is classified as a historical landmark, and while restoration is ongoing, the grounds can be visited. Because access and programming evolve as work progresses, the owners recommend confirming current visiting and observation options before travelling.↗↗

The atmosphere at the site is one of layered history: you stand where Mrázek cranked open a roof on a freezing winter night, where Freundlich decided what to keep running, where the building fell silent and was swallowed by the forest, and where a new generation is carefully bringing it back. The surrounding woodland, at just under 500 metres, still delivers the same clear air and dark skies that drew scientists here in the first place.↗