The Institut de mécanique céleste et de calcul des éphémérides (Bureau des longitudes) offers to the public an information service which is accessible :

  par courrier :
By E-mail :
By phone :
(from 10 a.m to 12 a.m and from 14 p.m to 16 p.m on working days)

Attention : The Institut de mécanique céleste does not receive the public

Attention : Before contacting us, it is recommended to visit our website. These servers contain the main informations sought by the public.

Our competence is limited to the solar system bodies ephemeris, the celestial mechanics, the observation of the solar system bodies and to the calendars..

  • For any information which is not our competence (weather, stellar physics, astronomy out of the solar system, geographical coordinates...), visit the useful links page
  • For the Earth artificial satellites ephemeris, visit the DLR/GSOC.
  • For weather information, visit Météo-France.
  • For geographical coordinates, visitInstitut Géographique National.
  • To know the schedules of the tides, visit the SHOM (Service hydrographique et océanographique de la marine).
  • For the identification of objects rumored extraterrestrial (meteorids) contact theMuséum national d'histoire naturelle (MNHN). you can write to :

    Or send an E-mail to
    give your name, your adress (postal or e-mail), the right spot where you found the rock, why you think it's a meteorid, its size, its shape and its weight.
  • For a request about legal information (e.g exact hours of the sunrise or the sunset, illumination in a given place...), it is better to write us to :


    to obtain an official response.
  • For a request about the reproduction of our works, texts or images of this website, fill the form on the copyright page.
  • For a professional scientific request, identify your correspondent by consulting the pages of the scientific teams and send him a message.

Nota : The informations requiring specific calculations are invoiced. Please contact us.

Caution : This Website was created with the Ministère de l'Education Nationale, the CNRS and the CNES support. Any use of the data published on this website requires the IMCCE agreement..