On April 18, 2007, a memorial plaque in honor of the astronomer and geodesist Peter Andreas Hansen was unveiled at the former observatory in Gotha, Jägerstraße 7, with the following inscription:
"This building, built in 1857 by court architect Scherzer, served as the home and workplace of Peter Andreas Hansen (1795 - 1874), an important astronomer and geodesist of the 19th century.
From 1825, as director of the Gotha Observatory, he made a significant contribution to the development of astronomy in his time through astrometric observations, calculations of the orbits of the moon and planets with their disturbances, and the construction of observation devices. As a geodesist, he carried out the land survey of the Duchy of Gotha from 1838, developing new calculation methods such as the "Hansen task" and later played a leading role in the European degree measurement. The "New Ducal Observatory" - moved into behind the house in 1859 - and its instruments were considered to be Model construction of an astronomical observatory. - German Society for Surveying - Thuringian State Association and Association of Publicly Appointed Surveying Engineers (LG Thuringia) in 2007."