Ondřejov 2-m telescope, Optical telescope at Ondřejov Observatory, Czech Republic.

The Ondřejov 2-meter telescope is the largest optical instrument in the Czech Republic, designed to observe stars and other celestial objects with high precision. Located at Ondřejov Observatory, the telescope continues to serve researchers studying distant astronomical phenomena and stellar data.

The telescope began operations in 1967 and marked a turning point in Czech astronomical research. This launch was part of a major expansion that established the observatory as the nation's premier observation facility.

The telescope represents a central component of the Astronomical Institute of the Czech Academy of Sciences, contributing to numerous scientific discoveries and research programs.

The telescope sits in a 21 m dome that rotates on 24 trolleys, with a 5 m observation slit closed by two 10-tonne sliding doors. A glazed visitor gallery on the dome's upper floor is separated from the telescope space to limit dust and temperature swings. The dome and the telescope pillar are kept apart by a 10 cm expansion gap.

The telescope cannot take photographs: it was built from the start to measure stellar spectra, revealing composition and motion. Its main targets were hot B-type stars at 10,000–30,000 K, and since 2017 it also measures spectra of stars hosting exoplanets.