[1] At the first such congress, in 1798, the French mathematician Jérôme Lalande had called for a coordinated search, in which each participating observatory would patrol a particular part of the sky.
[1][3] In 1798 Franz Xaver von Zach had organised and hosted the first European congress of astronomers at his observatory in Gotha.
Zach was also editor of the monthly journals Allgemeine Geographische Ephemeriden (since 1798) and Monatliche Correspondenz zur Beförderung der Erd- und Himmels-Kunde (since 1800).
Six astronomers were present to found the society on 20 September 1800, with Schröter as president and von Zach as director or secretary.
The founding members were:[1][5][6][7][4] The main workload for the society was the compilation of more precise star catalogues and to improve knowledge of spherical astronomy and coordinate systems.
The existence of such a body followed from the Titius-Bode law, a geometric series of the orbital radii from Mercury to Uranus, which has a gap at 2.8 astronomical units.
[1] As an international collaboration of astronomers, the Celestial police also noted the need for communication, both among participants and through a publication like von Zach's Monatliche Correspondenz zur Beförderung der Erd- und Himmels-Kunde.
[6][5][1] On 1 January 1801, apparently by coincidence and independent of the Celestial police, Piazzi was working on a star catalogue and found a moving object, the first minor planet, (1) Ceres.
This confirmed not only a planetary rather than a cometary orbit, it also enabled von Zach and Olbers to "recover" the minor planet, i.e. to find it again after its passage behind the Sun.
This could restore the Titius-Bode law and offered hope to find more minor planets, in particular at the crossing points of the orbits of Ceres and Pallas.