The Astronomy-Mathematics collection (AjAM) consists of the Old Observatory’s apparatus from the early 19th century to the 1960s, when a new observatory was opened in Tõravere.
The collection’s most famous items are the Fraunhofer Refractor (1824), which used to be the world’s largest reflecting telescope, the Meridian Circle (18..) used to determine the position of stars (its biggest achievement: the participation in the Bonn star catalogue), geodetic instruments and many others.
In the 20th century, the collection was expanded with the addition of the Carl Zeiss Refractor (1914) and several instruments made by local experts.
The Mathematics part of the collection consists of calculation devices through the ages (arithmometers, calculators, slide rulers, computers, etc.) and different teaching aids (mathematical models, geometric shapes).