• Osu Responsible: IPGP
  • Web site:
  • Data distribution
    All observatory magnetic data are freely available and currently distributed through:
  • Summary:
    The Bureau Central de Magnétisme Terrestre (BCMT) is a French organization founded in 1921 and attached to the Institut de Physique du Globe de Paris (Paris IPGP). The primary mission of the BCMT is to provide ground geomagnetic observations of the highest quality to the scientific community, in France and abroad. The recorded data allow studying, on time scales ranging from seconds to decades, all contributions to magnetic field measurements — e.g. magnetic fields generated in the core, the ionosphere and the magnetosphere. The BCMT also serves industrial, military and societal users, provided their needs are aligned with scientific needs.Two French institutions are involved in BCMT operations, IPGP and Ecole et Observatoire des Sciences de la Terre (EOST) in Strasbourg. Several other institutions, including CNRS-INSU and the Institut Polaire Français (IPEV), provide financial and/or human support. An international scientific council, set up in 2009, meets every two years to review BCMT activities and provides advice and recommendations to the BCMT.To achieve its mission, the BCMT operates a network of 17 magnetic observatories distributed on 6 continents, including the National Magnetic Observatory located in Chambon la Forêt, Loiret, and a repeat station network in metropolitan France. The BCMT observatory network represents about 15% of INTERMAGNET, the global network of magnetic observatories, and contributes to filling geographical gaps in scientifically interesting locations. The BCMT develops its own line of dedicated instruments, taking advantage of the Chambon la Forêt site where unique testing and calibration facilities are available.

    Several data products are distributed by the BCMT: preliminary one-second or one-minute data in real time (less than 5 min, 9 observatories) or near real time (less than 24 h, all observatories); quasi-definitive data with a one-month delay and definitive data with a one-year delay; repeat station data products such as a declination map and finally geomagnetic indices. BCMT data are available on its webpage (, and through other database as the INTERMAGNET’s webpage (


  • OSU responsible: EOST
  • Web site:
  • Summary :
    ISGI is in charge of the elaboration and the diffusion of the geomagnetic indexes and the lists of remarkable magnetic events recognized by IAGA (International Association of Geomagnetism and Aeronomy), on the basis of the report of magnetic observatories distributed on all the planet, with the help of its 6 Collaborating Institutes (ISGI-CI) .ISGI is the Reference Service for the validation, dissemination and management of geomagnetic indices thanks to its official Web portal.ISGI is in charge of the dissemination of all the IAGA bulletins on geomagnetic indexes.

    ISGI has a role of consulting and expertise with other members of the IAGA for everything concerning magnetic indexes.

    The ISGI host institute (EOST, Strasbourg) is in the calculation of preliminary, provisional and final values of magnetic activity indices aa and am recognized by IAGA in as short a time as possible.