Ephemeris DE403s 14-NOV-1995 Objects In This Ephemeris Name Id-code ------------------------------------ Sun...............................10 Mercury Barycenter.................1 Mercury..........................199 Venus Barycenter...................2 Venus............................299 Earth Moon Barycenter..............3 Moon.............................301 Earth............................399 Mars Barycenter....................4 Mars.............................499 Jupiter Barycenter.................5 Saturn Barycenter..................6 Uranus Barycenter..................7 Neptune Barycenter.................8 Pluto Barycenter...................9 Time Coverage The approximate time coverage for the bodies listed is: From: December 1, 1979 To : January 7, 2011 Status This ephemeris is a time subset of the JPL planetary ephemeris DE403. All of the bodies whose positions are modelled by DE403 are included. However, in order to make a reasonably compact ephemeris, only that portion of the ephemeris for the time span indicated above is included. The full DE403 ephemeris covers the interval from 29 April 1599 to 1 February 2200. As of November 13, 1995 this is the official ephemeris planned for use by the flight projects: Cassini, Mars Pathfinder, Mars Global Surveyor, Near Earth Asteroid Rendezvous. Note: This ephemeris is not suitable for use by those processing or using Galileo data. This is the latest and most accurate ephemeris distributed by JPL for the planets, sun and moon. We note that "formally" the positions of Mercury, Venus and Mars are not present in DE403. However, we have included these objects in this SPK file and set the offsets from to their respective system barycenters to zero. Mercury and Venus have no satellites. Consequently the system barycenters and centers of the bodies coincide. In the case of Mars, the offset of Mars from the Mars system barycenter cannot be detected with current technology. Moreover, simple calculations show that this offset can never exceed more than 10 cm. For this reason we include Mars with a zero offset from the system barycenter. Production/History of this Ephemeris This is a time subset of the full ephemeris DE403 which spans the time interval from 1599 APR 29 to 2200 FEB 01. This ephemeris represents an improvement over previous JPL planetary ephemerides. We reiterate some of the features of DE403 that are listed in the JPL Interoffice Memorandum listed in the "References" section below: -- The ephemeris is now based upon the J2000 reference frame of the International Earth Rotation Service (IERS). -- The standard sets of observations have been augmented with more recent observations. -- A number of new data types have been added to the observational data set. -- Some of the data reduction techniques have been refined. -- The modeling of the perturbations of asteroids upon the planetary orbits has been improved. The full DE403 ephemeris corrects a number of problems that have been identified for the moon prior to 1750 in the ephemeris DE118 . This SPK file was created from the JPL planetary ephemeris DE403 on June 1, 1995 by Hester Neilan of NAIF. It was created using the following script run by the NAIF program NIOSPK. ; de403s.bsp LOG FILE ; ; Created 1995-06-01/12:14:42.00. ; ; BEGIN NIOSPK COMMANDS LEAPSECONDS_FILE = /naif/data/naif0004.tls SPK_FILE = de403s.bsp SPK_LOG_FILE = de403s.log SOURCE_NIO_FILE = de403s.nio BODIES = 1 2 3 4 5 6 7 8 9 10 301 399 199 299 499 BEGIN_TIME = 1979 NOV 30 23:59:09.8169231 END_TIME = 2011 JAN 06 23:58:58.8159093 ; END NIOSPK COMMANDS Usage This ephemeris is suitable for use with the projects listed above and for general planning of terrestrial or satellite based observations of the planets and moon. However, satellites of planets, asteroids and comets are not provided in this ephemeris. Ephemerides for these objects may be obtained by contacting NAIF via the phone numbers or e-mail addresses listed below. Accuracy The JPL "DE" series of planetary ephemerides have been widely used throughout the astronomical community for over 20 years. They have been put to many different uses. A short list of the applications of these ephemerides includes: the construction of the tables in the "Astronomical Almanac" (for that matter all almanac producers world wide), planning of solar system observations with the Hubble Space Telescope, navigation of interplanetary missions, lunar laser ranging, solar system radar ranging, and solar system observations via VLBI. This latest ephemeris, DE403, represents state-of-the-art planetary and lunar positions. One method of describing the accuracy of the positions provided in DE403 is to consider the angles between various ephemeris objects as viewed from Earth. If the two objects observed are taken from the list (Sun, Mercury, Venus, Mars, Moon) the angles computed from the ephemeris positions are accurate to one or two milli-arcsecond.(This assumes all appropriate corrections are applied for light time, stellar aberration, and relativistic effects to the ephemeris derived positions.) If you add the barycenter of Jupiter to this list, uncertainty in ephemeris derived angles may grow to a few hundredths of an arcsecond. Adding Saturn, Uranus and Neptune will raise the uncertainty level to approximately 0.1 arcseconds. Finally, adding Pluto to the list raises the observable errors to 0.3 arcseconds for the present and increasing into the future. Radial distances to the centers of objects follow a similar trend. The radial distances between the inner objects of the solar system as computed via the ephemeris are accurate to 1 to 2 km. The distance between the Earth and the Jupiter Barycenter is accurate to better than 10 km. The uncertainty in the distances to Saturn, Uranus and Neptune are approximately 1000, 2000 and 4000 km respectively. For Pluto, the radial distance from earth may be in error up to 10000 km for the present and growing into the future. The above statements refer to the internal consistency of the ephemeris. These statements of accuracy also hold when comparing positions with the J2000 radio source reference frame adopted by the IAU and IERS. When comparing the position a planet (other than Pluto) as seen from earth with catalogue positions of stars, the DE403 positions of the planets are very likely to be more accurate than knowledge of the positions of the stars in the catalog (with the possible exception of the Hipparchos catalog). In the case of Pluto, the error in the DE403 position of Pluto is likely to be close to the error in the catalogue positions of stars. References Jet Propulsion Laboratory Interoffice Memorandum IOM 314.10-127 by E.M. Standish, X.X. Newhall, J.G. Williams and W.M. Folkner "JPL Planetary and Lunar Ephemerides, DE403/LE403" Inquiries If you have any questions regarding this ephemeris contact NAIF team member Bill Taber (818) 354-4279 btaber@spice.jpl.nasa.gov or NAIF group head Chuck Acton (818) 354-3869 cacton@spice.jpl.nasa.gov