The Astronomical Observatory of Trieste (OAT) is one of Italy's main centres for the study of astronomy. OAT's dual headquarters - in Castle Basevi and Villa Bazzoni - are located in Trieste; the observation station can be found outside the city in Basovizza, on the Carso, 10 kilometres to the north, where the sun's radioactivity is recorded daily.

Research fields range from the study of the sun, solar system, stars and Milky Way to the study of distant galaxies and cosmology.

OAT also works closely with a host of other institutions, including the Galileo National Telescope in the Canary Islands and the astronomical facilities of the European Southern Observatory in Chile. The center is also involved in the European Space Agency's (ESA) Planck space mission.

In 2001, OAT researchers, together with their international collaborators, obtained the first measurement of 238U outside the solar system. This measurement made it possible to have a new estimate of the age of the universe.