Ondrejov Observatory

The observatory sits on a wooded ridge above the village of Ondrejov, far enough from Prague for the sky to be usable. Its main instrument is a two-metre telescope, the largest in the country, in a dome that shows above the trees from the road. The site also carries solar telescopes, meteor cameras and radio antennas, and it began as a private observatory built by the industrialist Josef Jan Fric before passing to the state in the 1920s. Guided visits in the warm months go inside the dome to see the machine move, explain what a spectrograph is doing with the light, and take in the older buildings on the ridge.

History

The observatory was built in 1898 by the amateur astronomer and entrepreneur Josef Jan Frič as a private observatory, at 500 metres, away from the air and light of Prague, and on 28 October 1928 he donated it to the Czechoslovak state for the tenth anniversary of independence. Charles University ran it until 1953, when the Czechoslovak Academy of Sciences was founded and took it into its Astronomical Institute. In 1967 a telescope 2 metres wide was installed, at the time the 7th largest in the world and now the largest in the country. More than 700 minor planets have been discovered here, 23 of them credited directly to the observatory for 1997-2008, and the asteroid 7204 Ondřejov, discovered by Petr Pravec in 1995, is named after the village (Wikipedia, Ondřejov Observatory).

What's there

• The two-metre telescope - the country's largest, still booked with research time.
• The dome - the drive turning a structure the size of a house on its track.
• The solar telescopes - smaller instruments pointed at the sun rather than the night sky.
• The Fric buildings - the original private observatory that started the site.

When to go

Tours run mainly through the warmer half of the year and on announced open days, usually in Czech with occasional English, and places are limited enough that booking matters. Open days sometimes add evening observing on smaller instruments, weather permitting. Weekday visits are quieter. Nothing is on offer in deep winter.

Before you go

This is a working institute rather than a visitor attraction: no exhibition hall, no cafe, limited toilets and a tour that depends heavily on the guide you get. You look at the big telescope, not through it, since research time is booked by astronomers. Without a car it is a bus from Prague plus a twenty minute walk uphill, and the last buses back are early.

Nearby

The wooded bends of the Sazava valley south of the village.

Key facts