“JPL Horizons On-Line Ephemeris System”的意思、由来-开放百科全书

词条

JPL Horizons On-Line Ephemeris System

释义

Introduction
References
External links

JPL Horizons On-Line Ephemeris System provides easy access to key Solar System data and flexible production of highly accurate ephemerides for Solar System objects.

Osculating elements at a given epoch are always an approximation to an object's orbit (i.e. an unperturbed conic orbit or a "two-body" orbit). The real orbit (or the best approximation to such) considers perturbations by all planets, a few of the larger asteroids, a few other usually small physical forces, and requires numerical integration.

Jet Propulsion Laboratory (JPL) ephemerides do not use things such as periods, eccentricities, etc.^[1] Instead, JPL integrates the equations of motion in Cartesian coordinates (x,y,z), and adjusts the initial conditions in order to fit modern, highly accurate measurements of planetary positions.^[1]

As of August 2015, Horizons now uses ephemeris DE431.^[2]

Introduction

There are 3 ways to use the system:

WWW
Email
Telnet

References

1. ^¹{{cite web |date=2006-02-28 |title=Frequently Asked Questions (FAQ): What's the exact value of... |publisher=JPL Solar System Dynamics |author=Alan B. Chamberlin |url=http://ssd.jpl.nasa.gov/?faq#B06 |accessdate=2011-01-20}}
2. ^{{Cite web| last = Jet Propulsion Laboratory| title = HORIZONS User Manual| accessdate = January 10, 2016| date = August 28, 2015| url = http://ssd.jpl.nasa.gov/?horizons_doc#longterm| at="Long term ephemeridies" section}}

External links

JPL Horizons On-Line Ephemeris System (HORIZONS User Manual)

3 : Astrometry|Astronomy websites|JPL online services

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