The Swiss Ephemeris is the high precision ephemeris developed by Astrodienst, largely based upon the DExxx ephemerides from NASA's JPL. The original release in 1997 was based on the DE405/406 ephemeris. Since release 2.00 in February 2014, it is based on the DE431 ephemeris released by JPL in September 2013.

The Python Extension to the Swiss Ephemeris (or pyswisseph, or python-swisseph as you wish) brings the functionalities of the original C library to the Python programming language.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

The usual way. Download the package, open a terminal, uncompress the archive, go in the newly created directory, execute the setup script and celebrate.

If you are on a Debian or Ubuntu flavoured linux, you may have the libswe-dev package already installed. Which will be detected and used to build the module.

Compilation on windows systems goes the cmake way. You will have to get the software from their website.