Amateur project of astronomy software

French version
The purpose of JEphem (pronounce J-F-M) is to :
  • Write a free software to represent the sky and its movements.
  • Write a site describing the software, development methods and notions used to build the program.
  • In this page :
  • Free software
  • Astrosurf
  • The current version of the site and the software are development versions (see General presentation for more details).

    In this site :
  • To read first General presentation - in French only.
  • Ephemeris calculation Ephemeris calculation - presentation of astronomical notions used during development ; organisation of ephemeris calculation.
  • Sky map Sky map - just started, not much for the moment.
  • Curve plotting Curve plotting- just started, not much for the moment.
  • Date search Date search - just started, not much for the moment.
  • Informatic aspects of JEphem
    Informatic aspects - class organization ; links with javadoc pages, and source code. I couldn't find a convivial English term to designate "related to computers", so I use throughout this site derivatives from the French word "informatique".
  • Useful documents Library - Contains useful documents, like links to other sites.
  • Download area Download area - To get the program, a copy of this site, the sources...
  • Definition of terms and abreviations Glossary - If you find in the site a strange word, an abreviation... you should find its definition here.
  • Pending questions Questions - Remarks and questions raised by the development, problems I could not solve.
  • About the site About the site - Site map, about the author, contact.

      Free software

    JEphem is released under the GPL (General Public Licence).
    This licence was created by FSF FSF (Free Software Foundation) to protect and promote free software. The main danger, if a free software is not protected, is that a private enterprise takes it, betters it and turns it into a proprietary software. The original software, less developed, is then abandoned.

    To summarize, you have the following rights :
  • Use JEphem with no limit, distribute copies (given or sold) ;
  • Acces to the source code and use it for your own projects.

  • But you also have the following duties :
  • If you distribute the software, you must also distribute the original source code ;
  • If you use all or part of the software for your own project, the part of your project relying on JEphem must remain free.

  • If you want to use JEphem and GPL licence is a problem, contact me, and we'll try to find a solution.

    But the name "JEphem" is copirighted ; you can't use it for your own projects.

    Gnu project You can get the GPL licence on the web : ou par mail :
    Free Software Foundation, Inc., 59 Temple Place
    Suite 330, Boston, MA 02111, USA


    Visit Astrosurf This site is hosted by Astrosurf server, which hosts many astronomy sites (mainly in French) :
    The address just redirects to

    Among other things, this servers hosts an astro shop :

    Contact JEphem Top of the page