JPL Horizons On-Line Ephemeris System

<h2 id="ejection">Ejection</h2>
<p>Objects (such as <a href="/facts/C/1980_E1/bBRRYjMM">C/1980 E1</a>) on an outbound <a href="/facts/Hyperbolic_trajectory/4wEAXaez">ejection trajectory</a> will show an <a href="/facts/Orbital_eccentricity/WGlB4NBn">eccentricity</a> greater than 1, an <a href="/facts/Apoapsis_distance/VaL6ow9w">apoapsis distance</a> of AD= 9.99E+99 and an <a href="/facts/Orbit_period/94f56uh2">orbit period</a> of PR= 9.99E+99.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> For objects orbiting the Sun, this is best computed at an <a href="/facts/Epoch_(astronomy)/RDdj6SmA">epoch</a> (date) when the object is outside of the planetary region of the Solar System and no longer subject to notable planetary <a href="/facts/Perturbation_(astronomy)/og5hPpjQ">perturbation</a>. Due to the <a href="/facts/Galactic_tide/0X0cJblB">galactic tide</a> and <a href="/facts/List_of_nearest_stars/LLu2LmXq">passing stars</a> it is impossible to know if an object with a weak hyperbolic trajectory will truly be ejected or gently nudged back inward. The galactic tide and passing stars can also cause objects inbound from the Oort cloud to have a weakly hyperbolic trajectory.
</p>
<h2 id="overview-of-usage">Overview of usage</h2>
<p>There are 3 ways to use the system and all of them can be automated:
</p>
<ul><li><a href="/facts/WWW/wvnTrWFq">Web</a> (partial access)</li>
<li><a href="/facts/Email/6pD9GLtI">Email</a> (full access)</li>
<li><a href="/facts/Telnet/hxT0e85h">Telnet</a> (full access)</li></ul>
<p>The Horizons system was intended to be easy to use and should have a step-function learning curve.
</p>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://ssd.jpl.nasa.gov/horizons/">JPL Horizons On-Line Ephemeris System</a> (<a href="https://ssd.jpl.nasa.gov/?horizons_doc">HORIZONS User Manual</a>)</li>
<li><a href="https://ssd.jpl.nasa.gov/horizons_batch.cgi">HORIZONS Batch-Interface CGI</a> / <a href="https://ssd-api.jpl.nasa.gov/">JPL SSD/CNEOS API</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Alan B. Chamberlin (February 28, 2006). "Frequently Asked Questions (FAQ): What's the exact value of..." JPL Solar System Dynamics. Retrieved January 20, 2011. <a href="https://ssd.jpl.nasa.gov/?faq#B06" target="_blank">https://ssd.jpl.nasa.gov/?faq#B06</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Alan B. Chamberlin (February 28, 2006). "Frequently Asked Questions (FAQ): What's the exact value of..." JPL Solar System Dynamics. Retrieved January 20, 2011. <a href="https://ssd.jpl.nasa.gov/?faq#B06" target="_blank">https://ssd.jpl.nasa.gov/?faq#B06</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Jet Propulsion Laboratory (August 28, 2015). "HORIZONS User Manual". "Long term ephemeridies" section. Retrieved January 10, 2016. <a href="https://ssd.jpl.nasa.gov/?horizons_doc#longterm" target="_blank">https://ssd.jpl.nasa.gov/?horizons_doc#longterm</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Horizons output. "Barycentric Osculating Orbital Elements for Comet C/1980 E1 (Bowell)". Solution using the Solar System Barycenter. Ephemeris Type:Elements and Center:@0 (To be outside planetary region, inbound epoch 1950 and outbound epoch 2050) <a href="https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271980+E1%27&TABLE_TYPE=%27ELEMENTS%27&START_TIME=%271950-01-01%27&STOP_TIME=%272050-01-01%27&STEP_SIZE=%27100%20years%27&CENTER=%27@0%27&OUT_UNITS=%27AU-D%27" target="_blank">https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%271980+E1%27&TABLE_TYPE=%27ELEMENTS%27&START_TIME=%271950-01-01%27&STOP_TIME=%272050-01-01%27&STEP_SIZE=%27100%20years%27&CENTER=%27@0%27&OUT_UNITS=%27AU-D%27</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
</ol>

JPL Horizons On-Line Ephemeris System open-in-new

JPL Horizons On-Line Ephemeris System