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 is available under a dual licensing model. (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 is made available by its authors under a dual licensing system. The software developer, who uses any part of Swiss Ephemeris in his or her software, must choose between one of the two license models, which are

• a) GNU public license version 2 or later
• b) Swiss Ephemeris Professional License

If the developer choses the GNU GPL software license, he or she must fulfill the conditions of that license, which includes the obligation to place his or her whole software project under the GNU GPL or a compatible license. See http://www.gnu.org/licenses/old-licenses/gpl-2.0.html

If the developer choses the Swiss Ephemeris Professional license, he must follow the instructions below and purchase the Swiss Ephemeris Professional Edition from Astrodienst and sign the corresponding license contract.

The License grants you the right to use, copy, modify and redistribute Swiss Ephemeris, but only under certain conditions described in the License. Among other things, the License requires that the copyright notices and this notice be preserved on all copies.

Authors of the Swiss Ephemeris: Dieter Koch and Alois Treindl

The authors of Swiss Ephemeris have no control or influence over any of the derived works, i.e. over software or services created by other programmers which use Swiss Ephemeris functions.

The names of the authors or of the copyright holder (Astrodienst) must not be used for promoting any software, product or service which uses or contains the Swiss Ephemeris. This copyright notice is the ONLY place where the names of the authors can legally appear, except in cases where they have given special permission in writing.

Both types of licenses include the right to use the label 'Swiss Ephemeris Inside' on products. 

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. 

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.