Interface to Easily Download JPL Ephemerides

This software allows the user to have an easy access to JPL Horizons System to download ephemerides.

This interface was developed as a result of an Individual Research Project for the MSc course in Astronautics and Space Engineering 2014-2015. The software uses a Matlab object that establishes a TCP/IP between the computer of the user and Horizons via Telnet and that is used to forward the information entered by the user in the graphic user interface. None of the data produced are calculated by the software, but all of them are extracted from the data produced by Horizons. [1]

Two types of functions can be used to download ephemerides:
- Quick functions: They can be found in the folder “Quick functions”. They allow the user to download
very quickly ephemeris, but they do not provide all the capabilities that the Telnet interface of
Horizons can provide.
- GUI: This graphic user interface can be accessed by running the file runGui.m available in the folder
“GUI”. This interface is much more intuitive, easier to use and more practical to use than the
quick functions. It also covers almost all the capabilities of the Telnet interface of Horizons system.

Using the software, the user is able to download three types of ephemerides for a large number of bodies in the solar system:
- Observables: data about a body that can be observed, generally from a topocentric site on the
Earth, such as the right ascension, the declination, the azimuth, the elevation or the magnitude and
that can have a lot of useful applications in astronomy.
- Keplerian Elements: data about the orbit of a body and its position around its center.
- Cartesian Elements: data including the Cartesian position vector and the velocity vector with respect
to a center defined by the user.

In addition, two other types of data can be downloaded but only with the GUI:
- Characteristics: Inherent properties of the body selected by the user that can include the mass, the
volume, the mean radius, the density, etc.
- A list of close approaches of an asteroid or a comet with a planet or a moon during a laps of time
specified by the user

The software enables the user to output data in four different formats:
- Table in Matlab: the ephemeris generated in numerically save in different tables in the Workspace of
Matlab and that can immediately be used by the user. (GUI and quick functions)
- .txt file: the ephemeris is saved in a .txt file in a location specified by the user. (GUI and quick
functions)
- E-mail: the ephemeris is sent by mail to an address specified by the user (GUI only)
- Ftp link: the ephemeris can be accessed by the user via an Ftp link created by Horizons (GUI only)

An option to plot the ephemeris generated and an option to display the orbit of the body selected are also included in the GUI.

A documentation of the GUI is also included in the software and can be directly accessed from the GUI by clicking on the help button or from the folder “Help”.

[1] Giorgini J.D. Yeomans D.K. Chamberlin A.B. Chodas P.W. Jacobson R.A. Keesey M.S. Lieske J.H. Ostro S.J. Standish E.M. Wimberly, R.N. JPL's On-Line Solar System Data Service, Bulletin of the American Astronomical Society, volume 28. 1996. p. 1158.