The Ephemerides and Astronomical Data Server of the Bureau des Longitudes

Descamps, P., Thuillot, W., Arlot, J.-E., Montintin, A., Baron, N., Colas, F., Rocher, P., Bretagnon, P. F., Cavelier, F., Maulion, B.

Bureau des longitudes
URA 707 du CNRS
77 avenue Denfert Rochereau
F-75014 PARIS

A project of ephemerides and astronomical data server has been undertaken at Bureau des longitudes. The work performed in the fields of celestial mechanics, dynamics and astrometry give our laboratory two main functions.

First and foremost, the mission of Bureau des Longitudes is mainly dedicated to build and publish ephemerides of solar-system objects. The second major activity lies in improving the accuracy of the dynamical models of the motions of these objects.

The Internet network allowed us to plan the building of an ephemerides server. This server (, which is under development, will allow users to find coordinates of the main objects (planets, satellites, Moon, Sun, comets and asteroids) and to process with different changes of reference frames. The time period covered by these ephemerides will make them useful for observers which have access to the network in order to identify an object or for researchers who need to prepare or analyze observations. Thus the World Wide Web is a powerful mechanism for serving such data on the Internet network.

This server gives also access to our database on the natural satellites astrometric observations, named NSDC (Natural Satellites Data Center) which have been developped since 1991, with the support of the IAU.

Besides the possibility of archiving a wide set of useful static documents, another major interesting feature is to build a front-end query server by making available (via a CGI mechanism) in real time accurate positions, physical ephemerides of any solar system objects. This feature which is not available yet is currently under way.