Developers can license the Ephemeris library. Ephemeris users find 3200 years of read-made printable files of ephemerides, containing 19'200 print pages in PDF quality.

[German: wir bereiten eine deutsche Version dieser Seite zum Thema Schweizer Ephemeride vor].

The Swiss Ephemeris Free Edition is available under an Open Source license (see Download area).

The Swiss Ephemeris offers these advantages:

• The Swiss Ephemeris is based upon the latest planetary and lunar ephemeris, DE405/406, developed by NASA's Jet Propulsion Laboratory. The original integration, DE405, covered the years 3000 BC to 3000 AD and required 550 Mb of disk space. DE406 is a compressed version of DE405 which requires 200 MB while maintaining a precision of better than 1 m for the moon and 25 m for the planets. These data have been further compressed with sophisticated compression techniques developed by Astrodienst. The ephemeris now requires for the complete 6000 years only 5 Mb for all planets except the Moon, and 13 Mb for the Moon. This compressed ephemeris reproduces the JPL data with 0.001 arcseconds precision. 
• We have extended the timespan of the JPL ephemeris by numerical integration, so that Swiss Ephemeris covers the years 5400 BC to 5400 AD, a total of 10'800 years. For this extended timespan the ephemeris requires 32 Mbytes of ephemeris files.
• All transformation steps from the inertial timeframe of the JPL DE406 integration to the reference frame for astrological coordinates (true equinox of date), all corrections like relativistic aberration, deflection of light in the gravity field of the Sun etc. have been performed with utmost care and precision so that the target precision of 0.001 arcsec is maintained through all transformation steps. Never before has such a high precision ephemeris been available to astrologers. 
• Swiss Ephemeris contains three ephemerides. The user can choose whether he/she wants to use the original JPL DE406 data (if available at his/her site), the compressed Swiss Ephemeris data (the default) or a built in semianalytic theory by Steve Moshier. The Swiss Ephemeris package switches automatically to the available best precision ephemeris dependent on which installed ephemeris files it finds. Even without any stored ephemeris files, using the Moshier model, planetary positions with better than 0.1 seconds of arc precision are available (3 arcsec for the Moon). i
• In addition to the astronomical planets as contained in the JPL integration, we have included all other bodies and hypothetical factors which are of interest to the astrologer. We have used our own numerical integration program to provide ephemerides for ALL known asteroids. There are over 55'000 of them and nobody will be able to use them all. We distribute these extended asteroid files via our download area; there are also CDROMs available with large sets of asteroid files.
  Asteroid reaserachers may be interested in a December 1998 article in the Economist magazine about the naming of asteroids.
• Speed: The Swiss Ephemeris is precise and fast. On our Linux test machine, a 1000 MHz Pentium III, we compute 10'000 complete sets of planetary positions, i.e. 10'000 x 11 planets, in 9 seconds. This is 0.9 milliseconds for the complete set of exact planetary positions (consecutive 1 day steps).

How to license the Swiss Ephemeris:

• Swiss Ephemeris Free Edition under the Swiss Ephemeris Public License (SEPL): under this license the Swiss Ephemeris  is made available with complete source code to programmers free of charge. They can download the Swiss Ephemeris software from Astrodienst's website. 

The Public License is avaiable for two kinds developers: 
- those who  work only privately with the Swiss Ephemeris and make no software or services built upon the Swiss Ephemeris available  to others;
- programmers who publish their software with full source code for free under an equivalent open source model.
The Public License is free; those who want to receive the software and ephemeris files on a CDROM - instead of downloading it from the Internet - are charged a nominal fee of 39.90 Swiss Francs (approx. 28 USD). Support services are available for a fee if our time schedule and workload allows it. Online ordering here!
• Swiss Ephemeris Professional Edition: 

This version is available to those programmers who do not qualify for the Public License. Examples are
- Programmers who develop commercial software for sale, or build commercial services for which a fee is charged upon the use of the Swiss Ephemeris;
- Programmers who offer free software but do not want to publish their own source code under an equivalent open source license.

The Swiss Ephemeris Professional Edition can be purchased from Astrodienst for a one-time fixed fee for each commercial  programming project. The commercial license includes a CDROM with complete source code, prebuilt DLLs and libraries, a large set of binary ephemeris files and a four hours of support. 

If you want the Swiss Ephemeris Professional License for your software project, please proceed as follows:

• print the licensing contract in two copies 
• fill the printed copies out and sign them 
• mail them (not email, but real paper) to Astrodienst AG, attention Dr. Alois Treindl, Dammstr. 23, 8702 Zollikon, Switzerland. 
• do not forget the credit card details (if you live outside D,CH,A where we deliver with invoice)
• we will countersign the contract and send it together with the CDROM to you. We will charge your credit card when we ship the software. 
• If you are in a hurry, you can fax the contract to us, and we will ship (and charge the credit card) immediately. You still need to mail us the signed paper, to receive it countersigned. 

If you want the Swiss Ephemeris Free Edition for your software project, please proceed as follows:

• download the software
• make sure you understand the Public License conditions
• start programming

The documentation

The General Manual describes our work and the technical background. 

The Programmer's Manual describes the implementation details and the programming interface to the DLL resp. library functions. 

Demo Programs can be downloaded from ftp.astro.com/pub/swisseph/programs. A utility unzip.exe is also provided to unpack the download archive format.

• swewin.exe is a Windows program which computes complete horoscopes including houses and asteroids.
• swetest.exe is a MSDOS program which computes planetary positions. It is very versatile and can be used to create tables of ephemerides, or other tabular data for export to Excel.
  Issue the command
  swetest -?
  to get information about the features of swetest.