A magnetic observatory continuously measures the Earth's magnetic field.
In order to stay away from industrial activities and to avoid as much as possible any kind of external interference, the French National Magnetic Observatory has undergone several relocations since its construction in 1883:
- from 1841 to 1883: Irregular observations. Generally in harbours and at the "Observatoire de Paris"
- 1883 : Mascart creates the Observatory de St-Maur-des-Fossés (Val de Marne). Beginning of continuous observations.
- 1901 : due to the construction of the electric tram at St-Maur-des-Fossés, the Observatory is transferred to Val-Joyeux, in Villepreux (Yvelines).
- 1936 : industrial activity increase near Val-Joyeux led to the transfer of the Observatory to Chambon-La-Forêt (Loiret)
- 1952-2008 : creation of 18 magnetic observatories over 5 continents.
The objectives of the National Magnetic Observatory in Chambon-la-Forêt are multiple:
• it is an INTERMAGNET magnetic observatory,
• it is a centre for the processing, control and management of data for all the observatories operated by the BCMT.
• it is a geomagnetism research centre,
• it is a magnetic instrumentation research centre,
• it is a reference location for sensor calibration (for satellite or industrial use, etc.),
• It is a training centre for staff of the IPGP observatories and thus a place of international collaboration.