=============================================================================== ============================== Start Metadata ================================= =============================================================================== ============================== Metadata for Ceres ============================= IMPORTANT: This informal file release should not be used for "Category A" flight project purposes (involving the safety and success of spacecraft hardware and mission) without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127). That is, this particular object's orbit may be insufficiently well-determined, over the chosen time-span, to be suitable for some high-precision purposes. The "n-body" perturbed, numerically integrated SPK states were generated by: Horizons On-Line Ephemeris System Solar System Dynamics Group 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA information: http://ssd.jpl.nasa.gov/ connect : telnet ssd.jpl.nasa.gov 6775 inquiries : Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) Copyright (2001), California Institute of Technology. US Government sponsorship acknowledged. SPK file contents: ******************************************************************************* JPL On-Line Ephemerides Horizons ******************************************************************************* Target body : 1 Ceres {source: Horizons-SPK:JPL#24} Target SPK ID : 2000001 Coord center : Sun ( 10) {source: SB405-CPV-2} GM of center : 2.9591220828559109E-04 AU^3/D^2 Small perturbers: Pallas, Vesta {source: SB405-CPV-2} Small body GMs : 1.43E+01, 1.78E+01 km^3/s^2 Requested by : charles.acton@jpl.nasa.gov Execution date : Sun Mar 9 15:41:21 2003 (Pasadena time) Start time : 2003-Jan-01 00:00:00.0000 CT Stop time : 2013-Jan-01 00:00:00.0000 CT Step (days) : 0.5000 ******************************************************************************* Initial heliocentric osc. elements wrt ecliptic and mean equinox of J2000.0: EPOCH= 2451690.5 ! 2000-May-26.00 (CT) Residual RMS= .40152 EC= .07851582987375499 QR= 2.54965647340018 TP= 2451516.232585203 OM= 80.4917175009093 W= 73.94094048730319 IN= 10.5834474812652 Asteroid physical parameters: GM= 63.2 RAD= 474. ROTPER= 9.075 H= 3.34 G= .120 B-V= .720 (H RMS)= n.a. ALBEDO= .113 STYP= C ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A-posteriori SPK fidelity estimate (rel. to integrator): Max. error (3 std. dev) Time ------------------------ ------------------------ X: 0.3375029908946329D-03 m 2003-May-09 12:00:00.000 Y: 0.1368828318086390D-03 m 2010-Nov-20 12:00:00.000 Z: 0.7075677217247846D-04 m 2010-Nov-20 12:00:00.000 RSS: 0.3710144192818424D-03 m 2010-Nov-20 12:00:00.000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ =============================== Metadata for Hebe ============================ IMPORTANT: This informal file release should not be used for "Category A" flight project purposes (involving the safety and success of spacecraft hardware and mission) without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127). That is, this particular object's orbit may be insufficiently well-determined, over the chosen time-span, to be suitable for some high-precision purposes. The "n-body" perturbed, numerically integrated SPK states were generated by: Horizons On-Line Ephemeris System Solar System Dynamics Group 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA information: http://ssd.jpl.nasa.gov/ connect : telnet ssd.jpl.nasa.gov 6775 inquiries : Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) Copyright (2001), California Institute of Technology. US Government sponsorship acknowledged. SPK file contents: ******************************************************************************* JPL On-Line Ephemerides Horizons ******************************************************************************* Target body : 6 Hebe {source: Horizons-SPK:JPL#22} Target SPK ID : 2000006 Coord center : Sun ( 10) {source: SB405-CPV-2} GM of center : 2.9591220828559109E-04 AU^3/D^2 Small perturbers: Ceres, Pallas, Vesta {source: SB405-CPV-2} Small body GMs : 6.32E+01, 1.43E+01, 1.78E+01 km^3/s^2 Requested by : charles.acton@jpl.nasa.gov Execution date : Sun Mar 9 15:48:43 2003 (Pasadena time) Start time : 2003-Jan-01 00:00:00.0000 CT Stop time : 2013-Jan-01 00:00:00.0000 CT Step (days) : 0.5000 ******************************************************************************* Initial heliocentric osc. elements wrt ecliptic and mean equinox of J2000.0: EPOCH= 2446830.5 ! 1987-Feb-04.00 (CT) Residual RMS= .36095 EC= .2020957503693052 QR= 1.93471004683255 TP= 2447229.235865829 OM= 139.0744828899436 W= 238.6646455653694 IN= 14.7806240193129 Asteroid physical parameters: GM= n.a. RAD= 92.59 ROTPER= 7.274 H= 5.71 G= .240 B-V= .830 (H RMS)= .51339 ALBEDO= .268 STYP= S ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A-posteriori SPK fidelity estimate (rel. to integrator): Max. error (3 std. dev) Time ------------------------ ------------------------ X: 0.1141486182003398D-03 m 2008-Sep-11 12:00:00.000 Y: 0.1115442920697819D-03 m 2005-Oct-21 12:00:00.000 Z: 0.4578635765627765D-04 m 2004-Jul-30 12:00:00.000 RSS: 0.1660374255335957D-03 m 2008-Sep-11 12:00:00.000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ============================== Metadata for Iris ============================= IMPORTANT: This informal file release should not be used for "Category A" flight project purposes (involving the safety and success of spacecraft hardware and mission) without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127). That is, this particular object's orbit may be insufficiently well-determined, over the chosen time-span, to be suitable for some high-precision purposes. The "n-body" perturbed, numerically integrated SPK states were generated by: Horizons On-Line Ephemeris System Solar System Dynamics Group 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA information: http://ssd.jpl.nasa.gov/ connect : telnet ssd.jpl.nasa.gov 6775 inquiries : Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) Copyright (2001), California Institute of Technology. US Government sponsorship acknowledged. SPK file contents: ******************************************************************************* JPL On-Line Ephemerides Horizons ******************************************************************************* Target body : 7 Iris {source: Horizons-SPK:JPL#26} Target SPK ID : 2000007 Coord center : Sun ( 10) {source: SB405-CPV-2} GM of center : 2.9591220828559109E-04 AU^3/D^2 Small perturbers: Ceres, Pallas, Vesta {source: SB405-CPV-2} Small body GMs : 6.32E+01, 1.43E+01, 1.78E+01 km^3/s^2 Requested by : charles.acton@jpl.nasa.gov Execution date : Sun Mar 9 15:43:16 2003 (Pasadena time) Start time : 2003-Jan-01 00:00:00.0000 CT Stop time : 2013-Jan-01 00:00:00.0000 CT Step (days) : 0.5000 ******************************************************************************* Initial heliocentric osc. elements wrt ecliptic and mean equinox of J2000.0: EPOCH= 2445784.5 ! 1984-Mar-25.00 (CT) Residual RMS= .39171 EC= .2288264906215078 QR= 1.8401628975501 TP= 2445959.958033024 OM= 260.1348337772099 W= 144.8170839734063 IN= 5.510755393404044 Asteroid physical parameters: GM= n.a. RAD= 99.92 ROTPER= 7.139 H= 5.51 G= .150 B-V= .850 (H RMS)= 1.1519 ALBEDO= .277 STYP= S ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A-posteriori SPK fidelity estimate (rel. to integrator): Max. error (3 std. dev) Time ------------------------ ------------------------ X: 0.1217168259465995D-03 m 2004-Jul-30 12:00:00.000 Y: 0.1150665779330001D-03 m 2004-Jul-30 12:00:00.000 Z: 0.5772375934129186D-04 m 2008-Sep-11 12:00:00.000 RSS: 0.1771647128189397D-03 m 2008-Sep-11 12:00:00.000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ============================== Metadata for Vesta ============================= IMPORTANT: This informal file release should not be used for "Category A" flight project purposes (involving the safety and success of spacecraft hardware and mission) without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127). That is, this particular object's orbit may be insufficiently well-determined, over the chosen time-span, to be suitable for some high-precision purposes. The "n-body" perturbed, numerically integrated SPK states were generated by: Horizons On-Line Ephemeris System Solar System Dynamics Group 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA information: http://ssd.jpl.nasa.gov/ connect : telnet ssd.jpl.nasa.gov 6775 inquiries : Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) Copyright (2001), California Institute of Technology. US Government sponsorship acknowledged. SPK file contents: ******************************************************************************* JPL On-Line Ephemerides Horizons ******************************************************************************* Target body : 4 Vesta {source: Horizons-SPK:JPL#25} Target SPK ID : 2000004 Coord center : Sun ( 10) {source: SB405-CPV-2} GM of center : 2.9591220828559109E-04 AU^3/D^2 Small perturbers: Ceres, Pallas {source: SB405-CPV-2} Small body GMs : 6.32E+01, 1.43E+01 km^3/s^2 Requested by : charles.acton@jpl.nasa.gov Execution date : Sun Mar 9 15:35:29 2003 (Pasadena time) Start time : 2003-Jan-01 00:00:00.0000 CT Stop time : 2013-Jan-01 00:00:00.0000 CT Step (days) : 0.5000 ******************************************************************************* Initial heliocentric osc. elements wrt ecliptic and mean equinox of J2000.0: EPOCH= 2451851.5 ! 2000-Nov-03.00 (CT) Residual RMS= .4082 EC= .0898201081437658 QR= 2.148889631027962 TP= 2451614.595213277 OM= 103.950692716317 W= 149.500367784546 IN= 7.134583552433021 Asteroid physical parameters: GM= 17.8 RAD= 265. ROTPER= 5.342 H= 3.2 G= .320 B-V= .800 (H RMS)= n.a. ALBEDO= .423 STYP= V ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A-posteriori SPK fidelity estimate (rel. to integrator): Max. error (3 std. dev) Time ------------------------ ------------------------ X: 0.4161438404367958D-03 m 2012-Apr-15 12:00:00.000 Y: 0.2015896219076846D-03 m 2012-Apr-15 12:00:00.000 Z: 0.6043373102561262D-04 m 2012-Apr-15 12:00:00.000 RSS: 0.4663328290395656D-03 m 2012-Apr-15 12:00:00.000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ============================== Metadata for Eunomia =========================== IMPORTANT: This informal file release should not be used for "Category A" flight project purposes (involving the safety and success of spacecraft hardware and mission) without first contacting Donald.K.Yeomans@jpl.nasa.gov (Supervisor, Solar System Dynamics Group, 818-354-2127). That is, this particular object's orbit may be insufficiently well-determined, over the chosen time-span, to be suitable for some high-precision purposes. The "n-body" perturbed, numerically integrated SPK states were generated by: Horizons On-Line Ephemeris System Solar System Dynamics Group 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA information: http://ssd.jpl.nasa.gov/ connect : telnet ssd.jpl.nasa.gov 6775 inquiries : Jon.D.Giorgini@jpl.nasa.gov (program author; 818-393-3107) Copyright (2001), California Institute of Technology. US Government sponsorship acknowledged. SPK file contents: ******************************************************************************* JPL On-Line Ephemerides Horizons ******************************************************************************* Target body : 15 Eunomia {source: Horizons-SPK:JPL#21} Target SPK ID : 2000015 Coord center : Sun ( 10) {source: SB405-CPV-2} GM of center : 2.9591220828559109E-04 AU^3/D^2 Small perturbers: Ceres, Pallas, Vesta {source: SB405-CPV-2} Small body GMs : 6.32E+01, 1.43E+01, 1.78E+01 km^3/s^2 Requested by : charles.acton@jpl.nasa.gov Execution date : Sun Mar 9 15:45:58 2003 (Pasadena time) Start time : 2003-Jan-01 00:00:00.0000 CT Stop time : 2013-Jan-01 00:00:00.0000 CT Step (days) : 0.5000 ******************************************************************************* Initial heliocentric osc. elements wrt ecliptic and mean equinox of J2000.0: EPOCH= 2449485.5 ! 1994-May-13.00 (CT) Residual RMS= .29451 EC= .1871115785818805 QR= 2.148709054688497 TP= 2449510.164322489 OM= 293.5604712631028 W= 97.38667612662286 IN= 11.75637304799742 Asteroid physical parameters: GM= n.a. RAD= 127.67 ROTPER= 6.083 H= 5.1556 G= .150 B-V= .840 (H RMS)= .47074 ALBEDO= .209 STYP= S ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A-posteriori SPK fidelity estimate (rel. to integrator): Max. error (3 std. dev) Time ------------------------ ------------------------ X: 0.2072401480127762D-03 m 2010-Oct-19 12:00:00.000 Y: 0.2108088529990038D-03 m 2011-Feb-24 12:00:00.000 Z: 0.1243476865801906D-03 m 2011-Feb-24 12:00:00.000 RSS: 0.3207042229359605D-03 m 2011-Feb-24 12:00:00.000 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ******************************************************************************* ============================== Metadata for JUP204 ============================ Satellite Ephemeris File Release Satellite Ephemeris: JUP204 Location: ssd.jpl.nasa.gov/pub/eph/satellites/nio/jup204.long.nio Location: ssd.jpl.nasa.gov/pub/eph/satellites/xsp/jup204.long.xsp Size(nio): 182941696 bytes Enter SATEPHMERGE/11 06-May-2002 11:50:57.218 linked 31-May-2001 09:59:55 Integration fit to all data - JUP204.17 Ephemeris Version Number: 11 Timespan from JED 2424148.500(29-DEC-1924) to JED 2460676.500(01-JAN-2025) File Epoch Julian Date: 2450464.50 Master Interval: 4.0000 Days Equinox Reference Julian Date: 2451545.00 Planetary Ephemeris Number: DE-0405/LE-0405 Bodies on the File: Name Number GM NDIV NDEG Model Io 501 5.959915965308669E+03 4 13 SATINT Europa 502 3.202733759136212E+03 4 13 SATINT Ganymede 503 9.887828949380846E+03 4 10 SATINT Callisto 504 7.179291580537229E+03 2 11 SATINT Amalthea 505 5.000000000000000E-01 8 12 SATINT Thebe 514 0.000000000000000E+00 8 11 SATINT Jupiter 599 1.266865343445600E+08 2 11 SATINT System 1.267127646148144E+08 Additional Constants on the File: AU 1.495978706910000E+08 RADIUS 7.149200000000000E+04 J502 1.469629661121321E-02 J503 4.498228966045162E-07 J504 -5.851389988636109E-04 J505 0.000000000000000E+00 J506 2.549166341526796E-05 POLTIM 2.451545000000000E+06 ZACPL5 2.680572431605116E+02 ZDEPL5 6.449570618380706E+01 DACPL5 -1.605467941035296E-04 DDEPL5 5.556874934637158E-03 WPL5 2.849500000000000E+02 WDP5 8.705366420000000E+02 GM0600 3.794062976400000E+07 GM0700 5.794548600000000E+06 GM0800 6.836534900000000E+06 GM1000 1.327132332402215E+11 Chebyshev interpolation error: 0.5/500.0 meters Release to: Horizons/NAIF Time: 20-May-2002 15:16:16 Preparer: R. A. Jacobson Comments: Galilean satellite, Amalthea, and Thebe ephemerides from a fit to all Jupiter data through the Io33 encounter. These are a preliminary version of the the ephemerides from the Jovian data analysis. Later versions will refine the models. The Galileo data set is complete with the exception of the final Amalthea encounter. ============================== Metadata for SAT132 ============================ Satellite Ephemeris File Release Satellite Ephemeris: SAT132 Location: ssd.jpl.nasa.gov/pub/eph/satellites/nio/sat132.nio Location: ssd.jpl.nasa.gov/pub/eph/satellites/xsp/sat132.xsp Size(nio): 73463808 bytes Enter SATEPHMERGE/12 04-Feb-2003 08:39:42.481 linked 21-Jan-2003 14:48:50 Fit to Earthbased, Voyager, and HST data from 1966 to 2003 Ephemeris Version Number: 12 Timespan from JED 2439416.500(18-OCT-1966) to JED 2460692.500(17-JAN-2025) File Epoch Julian Date: 2453006.50 Master Interval: 18.0000 Days Equinox Reference Julian Date: 2451545.00 Planetary Ephemeris Number: DE-0405/LE-0405 Bodies on the File: Name Number GM NDIV NDEG Model Mimas 601 2.562248694441524E+00 24 14 SATORB Enceladus 602 5.770493590875791E+00 24 11 SATORB Tethys 603 4.120925828680387E+01 12 15 SATORB Dione 604 7.312857497096579E+01 8 15 SATORB Rhea 605 1.545888057352435E+02 6 15 SATORB Titan 606 8.978034767893490E+03 4 15 SATORB Hyperion 607 7.200000000000000E-01 4 10 SATORB Iapetus 608 1.317883630267206E+02 2 10 SATORB Saturn 699 3.793128449712308E+07 4 15 SATORB System 3.794067229963528E+07 Additional Constants on the File: AU 1.495978706910000E+08 RADIUS 6.033000000000000E+04 J602 1.629462560191289E-02 J604 -9.197277823946756E-04 J606 9.975895864684476E-05 POLTIM 2.444556491238426E+06 ZACPL6 4.059550000000000E+01 ZDEPL6 8.353812000000001E+01 DACPL6 -4.229000000000000E-02 DDEPL6 -4.440000000000000E-03 WPL6 1.986092467861570E+02 WDP6 8.107939024000000E+02 612GM 0.000000000000000E+00 613GM 0.000000000000000E+00 614GM 0.000000000000000E+00 GM5 1.267127678577960E+08 GM10 1.327124400179870E+11 Chebyshev interpolation error: 12.70 meters Release to: Cassini/Horizons/NAIF Time: 05-Feb-2003 11:53: 9 Preparer: R. A. Jacobson Comments: Integration fit to Voyager and Earthbased observations (1966-2003). The ephemeris the one determined during the Voyager Saturn orbit reconstruction reported in AAS paper AAS 03-198. ============================== Metadata for URA027 ============================ Satellite Ephemeris Release Satellite Ephemeris: URA027.2 Number of Satellites = 6 File location: murphy:/home2/raj/Ephemerides/Uranus/ura027.2.nio Enter SATGEN 16-JUN-1994 11:38:36 linked 24-MAR-1994 15:25:33 GUST86 theory Ephemeris Version Number: 3 Timespan from JED 2444239.50( 1-JAN-1980) to JED 2455199.50( 3-JAN-2010) File Epoch Julian Date: 2444239.50 Master Interval = 20.0000 Days Equinox Reference Julian Date: 2433282.50 Planetary Ephemeris Number: DE-0130/LE-0130 Orbital Motion Model: GUST Bodies on the File: Name Number GM NDIV NDEG Mirand 705 4.346127202805427E+00 10 14 Ariel 701 8.608449582032800E+01 5 15 Umbrie 702 8.399390758106858E+01 4 14 Titani 703 2.299368431723383E+02 2 15 Oberon 704 1.999615497251917E+02 2 14 Uranus 799 5.793950209634619E+06 2 13 System 5.794554532558121E+06 Additional Constants on the File: AU 1.495978706136889E+08 RADIUS 2.620000000000000E+04 J702 3.346100000000000E-03 J704 -3.210000000000000E-05 J706 0.000000000000000E+00 ZACPL7 7.660666666666667E+01 ZDEPL7 1.503222222222222E+01 DACPL7 0.000000000000000E+00 DDEPL7 0.000000000000000E+00 WPL7 3.600000000000000E+02 WDP7 -5.011600928000000E+02 POLTIM 2.433282500000000E+06 Release to: NAIF Date: 16-JUN-1994 Time: 13:35:41 Preparer: R.A. Jacobson Comments: Ephemeris based on the GUST86 theory. Chebyshev polynomial fit accuracy (not the ephemeris accuracy) is 500 meters RMS. File contains 10273792 bytes. ============================== Metadata for NEP016 ============================ Satellite Ephemeris File Release Satellite Ephemeris: NEP016.6 Location: ssd.jpl.nasa.gov/pub/eph/satellites/nio/nep016.nio Location: ssd.jpl.nasa.gov/pub/eph/satellites/xsp/nep016.xsp Size(nio): 11876352 bytes Enter SATMERGE/7 26-AUG-2002 10:33:02 linked 20-JAN-2000 11:28:50 Extended version of NEP016 Ephemeris Version Number: 7 Timespan from JED 2444236.500(29-DEC-1979) to JED 2469440.500(30-DEC-2048) File Epoch Julian Date: 2447680.50 Master Interval: 4.0000 Days Equinox Reference Julian Date: 2451545.00 Planetary Ephemeris Number: DE405 /LE405 Bodies on the File: Name Number GM NDIV NDEG Model Triton 801 1.427867949141134E+03 1 15 SATINT Nereid 802 0.000000000000000E+00 1 10 SATINT Neptune 899 6.835107010942784E+06 1 10 SATINT System 6.836534878891925E+06 Additional Constants on the File: AU 1.495978706094335E+08 RADIUS 2.522500000000000E+04 J802 3.410473591490029E-03 J804 -3.470308578301639E-05 ZACPL8 2.992721978383362E+02 ZDEPL8 4.294704243322104E+01 DACPL8 6.263280478897472E-01 DDEPL8 -6.052487120895595E-02 WPL8 3.320826385333162E-01 WDP8 0.000000000000000E+00 POLTIM 2.447763500000000E+06 J803 0.000000000000000E+00 RAREF8 2.989525829488086E+02 DEREF8 4.331345012848936E+01 ZPRPL8 5.231800995129119E+01 GM1300 1.328836807306296E+11 GP13 1.328836807306296E+11 Ephemeris Accuracy (km,sec) - 1 sigma: Name Radial Downtrack Normal Period Triton 13.000 40.000 45.000 0.400000 Nereid 800.000 1900.000 500.000 600.000000 Chebyshev interpolation error: 100.0 meters Release to: Horizons/NAIF Time: 26-Aug-2002 10:39:45 Preparer: R. A. Jacobson Comments: Extension of the original Neptunian ephemeris file to accommodate future mission studies. The extension was merged onto to the original. ============================== Metadata for DE405 ============================= A memo describing the creation of the DE405 generic planet ephemeris is available from NAIF or from the author: Dr. Myles Standish of JPL's Solar System Dynamics Group. Because this memo was produced using the TeX processor and includes numerous equations, tables and plots, only a small extract of it can be included here as plain ASCII text. >>> Beginning of extract from Standish's DE405 memo <<< JET PROPULSION LABORATORY INTEROFFICE MEMORANDUM IOM 312.F - 98 - 048 August 26, 1998 TO: Distribution FROM: E M Standish SUBJECT: JPL Planetary and Lunar Ephemerides, DE405/LE405 INTRODUCTION The latest JPL Planetary and Lunar Ephemerides, "DE405/LE405" or just "DE405," have been released and are now available. DE405 represents an improvement over its predecessor, DE403, described in detail by Standish et al (1995), and hereafter referred to as the "DE403 Memo." Many of the data sets, reduction techniques, etc. are the same as those used for DE403; they will not be described at length in this memo. Instead, this memo concentrates on the differences: additional data, refinements to the reduction techniques, etc. The memo discusses the improvement in the orientation of the ephemerides onto the (J2000) International Celestial Reference Frame (ICRF). It shows the increased observational data set used for DE405 and the associated residuals. There is a description of the improved method for modeling the perturbations of asteroids upon the planetary orbits. The individual ephemerides in DE405 are compared with those of DE403. Tables are included of the initial conditions and dynamical constants, resulting from the least squares fitting process and used for the integration. II. ORIENTATION OF DE405 As has been discussed often, the ephemerides of the four innermost planets along with the moon and the sun are all well-known with respect to each other because of the accurate ranging observations to which the ephemerides are adjusted. In turn, the orientation of this inner system onto the ICRF is also accurately determined, mainly by the VLBI observations of the Magellan Spacecraft orbiting Venus, but also somewhat by VLBI observations of the Phobos Spacecraft approaching Mars, a frame- tie linkage using ground surveys and lunar laser ranging (LLR)data, and the range observations of the Viking Spacecraft on the surface of Mars. Some of the Magellan VLBI observations are new since DE403. These data are discussed in the next section. It is believed that the orientation of the whole inner planet ephemeris system of DE405 is now accurate to about 0.001 arcseconds. A verification of this estimate was provided by the arrival of the Pathfinder Spacecraft at Mars in July 1997, where the ephemeris error was about 0.001 arcseconds, corresponding to 1 km at that distance; it was mostly in the down-track direction. Ephemerides of the outer planets rely almost entirely upon optical observations these were initially referenced to various stellar catalogues, then transformed onto the FK4 using the formulae of Schwan (1983), then onto the FK5 system by applying the equinox offset and motion parameters of Fricke (1982), and finally onto the ICRF using tentative transformation tables supplied by Morrison (1996). {Substantial intervening text that included equations has been left out.} CONCLUSION DE405 represents the most accurate planetary positions available. Certainly, they are not perfect; extrapolation forward or backward in time will always show some amount of deterioration. Subsequent improvements will continue with further acquisition of observational measurements. >>> End of extract from Standish's DE405 memo <<< =============================================================================== ================================ End Metadata ================================= ===============================================================================