HORIZONS System

The JPL HORIZONS on-line solar system data and ephemeris computation service provides access to key solar system data and flexible production of highly accurate ephemerides for solar system objects ( 995366 asteroids, 3679 comets, 209 planetary satellites, 8 planets, the Sun, L1, L2, select spacecraft, and system barycenters ). HORIZONS is provided by the Solar System Dynamics Group of the Jet Propulsion Laboratory.

The HORIZONS system can be accessed using any of the following methods:

NOTE: Although the web-interface to HORIZONS provides nearly all capabilities of the primary telnet interface (and email interface), it does not provide the following: Small-body PARAMETER-MATCHING population searches

(use the small-body search engine as an alternative)

(use the small-body search engine as an alternative) Integration of USER-INPUT ORBITS

SPK BINARY FILE production

CLOSE-APPROACH TABLES

HORIZONS Documentation - (updated 2019-Dec-10)

Complete documentation is available in the following formats:

HTML document

PDF document (temporarily unavailable)

(temporarily unavailable) PostScript document (temporarily unavailable)

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Using the telnet Interface

The HORIZONS system can be accessed directly by connecting to "horizons.jpl.nasa.gov" via telnet port 6775. This will initiate a text-only "VT100" terminal session that accesses all HORIZONS functions. You will be taken through a series of prompts that will ask you questions needed to generate the desired information. To initiate such an interactive session from a UNIX/LINUX system command line, type:

telnet horizons.jpl.nasa.gov 6775

If your connection is refused, it is likely due to a firewall or security restriction at your end. In either case, please contact your local computer system administrator or consult your telnet program documentation if you need more help. Since no password or security information is exchanged, you may be able to request a firewall exception from your institution.

A HORIZONS terminal session can also be started from within a web-browser, by entering this URL in your browser:

Using the email Interface

The HORIZONS system can be accessed using email to submit batch-style input files. Instructions on how to access the email server, including a complete detailed example, is available by sending an email message to horizons@ssd.jpl.nasa.gov with the subject "BATCH-LONG". Alternatively, you can access the instructions via FTP.

IMPORTANT: Please be sure your email client is sending content as plain ASCII text. Failure to do so may result in no response from the system or an error message, even when your job-content appears perfect from within your email client. A helpful guide to suitably configure various email clients is available via this link.