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JPL PLANETARY AND LUNAR EPHEMERIDES : Export Information [12 October 2007]
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INTRODUCTION
------------
Selected JPL Planetary and Lunar Ephemerides are available to outside users.
Subroutines are availabe to read the ephemerides to obtain the RECTANGULAR
COORDINATES (x,y,z) of the sun, moon, and nine major planets at the desired
general relativistic COORDINATE TIME (TDB). The user is then able to compute
angular coordinate, light times, etc. as required. Such computations usually
require significant programming experience and familiarity with Earth rotation
calculations, access to variable Earth orientation calibrations, knowledge
of relativistic effects, etc.
We suggest for the more casual user, JPL's interactive website and telnet
service, "Horizons", which provides a wide variety of astronomical
information and which uses the full precision of our ephemerides. See
the website, "http://ssd.jpl.nasa.gov/".
For those who truly need the high-precision, basic JPL ephemerides, there
are two methods of acquiring the ephemerides: 1) from this site via ftp and
2) via a CRrom from the publisher, Willmann-Bell (see Appendix B).
The final goal of the installation process is the successful execution
of the main program "TESTEPH.F". This program reads and interpolates
planetary and lunar coordinates from a binary direct-read ephemeris file
and compares these results against corresponding numbers produced at JPL.
"TESTEPH.F" uses the subroutines which are of eventual interest to the user.
It is strongly suggested that a potential user first read through this
README in its entirety. This will provide an idea of what is involved in
both the installation and in the usage of the ephemeris package.
This README contains the following sections;
Introduction
Location of the files
What to do (ftp and install)
Unix users vs. other users
Contents to be retrieved by the user (which files to get via ftp)
Brief item description: what each retrieved item is for
Available ephemerides (which ones; what years are covered)
Ephemeris sizes (how big the files are)
References (publications describing the ephemerides)
Software description (the subroutines which provide ephemeris information)
Software Usage (calling sequances, etc.)
Constants on the Ephemeris Files : what ephemeris constants are on the files
Assistance (only in case of emergency)
Appendix A : The internal format of the ephemeris files
Appendix B : CDrom available from Willmann-Bell
Appendix C : Corrections to the software on the CDroms
Appendix D : Documentation of DE405 and DE406
Appendix E : Versions of the software in various languages (from
outside sources)
*******************************************************************************
LOCATION
--------
The ephemeris package is available over Internet from the anonymous ftp server:
ssd.jpl.nasa.gov
When connected, "cd pub/eph/planets/"
******************************************************************************
WHAT TO DO
----------
Retrieve the items, listed in the next sections, from the anonymous ftp site.
Read the "usrguide", especially the parts about "NRECL" and "KSIZE"
[Note: For UNIX-based users, some ephemeris files are available in binary
form, ready for immediate installation on the user's computer. For all
others, the ephemeris is supplied in ASCII format and must be converted
(a one-time only process) into binary format for installation; software
is supplied for this conversion.
******************************************************************************
CONTENTS TO BE RETRIEVED BY THE USER
------------------------------------
*** UNIX users: retrieve the following 7 items:
(via ftp from ssd.jpl.nasa.gov)
/pub/eph/planets/usrguide
/pub/eph/planets/fortran/testeph.f
/pub/eph/planets/fortran/selcon.f
/pub/eph/planets/fortran/binmerge.f
/pub/eph/planets/fortran/binshort.f
/pub/eph/planets/unix/deXXX/unxSYYYY.XXX (multiple files)
/pub/eph/planets/test-data/testpo.XXX
where "XXX" is a three-digit number of the desired planetary ephemeris (e.g. 403),
and "SYYYY" is the starting year of each particular ephemeris block
("S" is the sign : "p" for + and "m" for -).
The UNIX binary files come in 50-year blocks (3.8-4.7 Mbytes each,
depending upon the ephemeris). Once they are installed on the user's
computer, contiguous blocks may be merged together to form a single
ephemeris file; this is done using "binmerge.f".
*** non-UNIX users: retrieve the following 9 items:
(one is in the directory :/usr1/ftp/" upon entry)
/pub/eph/planets/usrguide
/pub/eph/planets/fortran/testeph.f
/pub/eph/planets/fortran/selcon.f
/pub/eph/planets/fortran/asc2eph.f
/pub/eph/planets/fortran/binmerge.f
/pub/eph/planets/fortran/binshort.f
/pub/eph/planets/ascii/DExxx/ascSYYYY.XXX (multiple files)
/pub/eph/planets/ascii/DExxx/header.XXX
/pub/eph/planets/test-data/testpo.XXX
where "SYYYY" is the starting year of each particular ephemeris block
("S" is the sign : "p" for + and "m" for -) and "XXX" is the ephemeris
number: 200, 403, 405, or 406. See choices below for different
ephemerides.
The ASCII files come in 20-year blocks (about 3.5 Mbytes each). The
blocks are converted into binary blocks on the user's computer, using
"asc2eph.f"; then, contiguous binary blocks may be merged together to
form a single ephemeris file using "binmerge.f"; or, a smaller portion
of an ephemeris file may be extracted from a larger file using
"binshort.f".
******************************************************************************
BRIEF ITEM DESCRIPTION
-----------------------
"usrguide" : User's Guide containing instructions for obtaining and using
the ephemerides, including the usage of the subroutines and
the testing of the software package.
"testeph" : Software Package containing a main program which uses the
reading and interpolating subroutines. This program
compares the results with similar runs made at JPL in order
to ensure that the ephemeris is installed and being read
correctly.
The reading and interpolating subroutines included in
"testeph", along with the ephemeris file(s) themselves, are
the items which are of eventual interest to the user.
"testpo" : Test results computed at JPL; these are input by the program
"testeph" and are used for testing the ephemeris
installation. There is a different "testpo" for each
different ephemeris; they must match or the test will not
work correctly.
"binmerge" : Program to merge two adjoining binary ephemerides.
"binshort" : Program to extract a portion of an ephemeris from a larger
file.
for UNIX users
--------------
"unxSYYYY.XXX" : Binary ephemeris files from JPL Ephemeris DEXXX, covering 50
years, starting in the year SYYYY ("p/m" for "+/-"). The
pieces may be used separately, or the 50-year files
(300-year files for DE406) may be merged into a single
ephemeris file using the program, "binmerge.f". Also, a
shorter-span ephemeris may be extracted from a longer one
using the program, "binshort.f".
for non-UNIX users
--------------
"asc2eph.f" : A one-time conversion program which converts the ephemeris
from ASCII format into binary form.
"ascSYYYY.XXX" : ASCII ephemeris files from JPL Ephemeris DEXXX, each
covering 20 years, starting in the year SYYYY ("p/m" for
"+/-"). The 20-year blocks may be converted separately
into binary ephemeris files using "asc2eph" or they may
be combined into a single ASCII files and then converted
into a single binary file. Subsequently, separate binary
files may be merged into a single ephemeris file using
the program, "binmerge.f". Also, a shorter-span ephemeris
may be extracted from a longer one using the program,
"binshort.f".
"header.XXX" : Header information for ephemeris deXXX, needed by "asc2eph.f".
******************************************************************************
AVAILABLE EPHEMERIDES
---------------------
DE200 : (includes nutations but not librations)
JED 2305424.5 (1599 DEC 09) to JED 2513360.5 (2169 MAR 31)
This ephemeris has been the basis of the Astronomical Almanac since
1984. It is based upon the dynamical equator and equinox of J2000
(see Standish, 1982 and Standish, 1990).
DE403 : (includes both nutations and librations)
JED 2433264.5 (1949 DEC 14) to JED 2469808.5 (2050 JAN 02)
Tied to the International Celestial Reference Frame through comparison of
UTPM estimates from Lunar Laser Ranging and VLBI
DE405 : (includes both nutations and librations)
JED 2305424.50 (1599 DEC 09) to JED 2525008.50 (2201 FEB 20)
Tied to the International Celestial Reference Frame through VLBI
observations of the Magellan spacecraft in orbit around Venus.
DE405 was created in May-June 1997.
DE406 : a "Long Ephemeris" (includes neither nutations nor
librations)
JED 0624976.50 (-3001 FEB 04) to 2816912.50 (+3000 MAY 06)
This is the same ephemeris as DE405, though the accuracy of the
interpolating polynomials has been lessened (interpolation on the
64-day mesh points remains exact, however). For DE406/LE406, the
interpolating accuracy is no worse than 25 meters for any planet and
no worse than 1 meter for the moon.
DE406 requires about 10 megabytes for each 300-year block.
DE410 : Specialzed ephemeris used for Mars Exploration Rover navigation
(DE409 is identical except for the reference vale uf GM for Mars)
Tied to ICRF by VLBI observations of Mars Global Surveyor and
Mars Odyssey.
Created 24 April 2003
DE413 : A special ephemeris to update the orbit of Pluto to aid in planning
for an accolutation of a relatively bright start by Pluto's satellite Charon
on 11 July 2005.
Created 4 November 2004
DE414 : An ephemeris fit to ranging data from MGS and Odyssey through 2003
in addition to many other data types for all planets.
Integration covers 1599 to 2201. Some aspects are documented in
Alex S Konopliv et al., Icarys vol 182, pp 23-50 (2006).
Created May 2005
******************************************************************************
EPHEMERIS SIZES (ftp blocks)
----------------------------
de200 de403 de405 de406
UNIX binary (50-year blocks) : 3.8 Mb 4.1 Mb 4.7 Mb
UNIX binary (300-year blocks) : 10.0 Mb
ASCII (20-year blocks) : 5.2 Mb 6.4 Mb
ASCII (25-year blocks) : 6.1 Mb
******************************************************************************
REFERENCES
----------
Newhall, X X, Standish, E.M. and Williams, J.G.: 1983, "DE102: a numerically
integrated ephemeris of the Moon and planets spanning forty-four centuries",
Astronomy & Astrophysics, vol. 125, pp. 150-167.
Standish, E.M.: 1982, "Orientation of the JPL Ephemerides, DE200/LE200, to
the Dynamical Equinox of J2000", Astronomy & Astrophysics, vol. 114,
pp. 297-302.
Standish, E.M.: 1990, "The Observational Basis for JPL's DE200, the
planetary ephemeris of the Astronomical Almanac", Astronomy & Astrophysics,
vol. 233, pp. 252-271.
Standish, E.M., Newhall, X X, Williams, J.G. and Folkner, W.F.: 1995,
"JPL Planetary and Lunar Ephemerides, DE403/LE403", JPL IOM 314.10-127.
Standish,E.M.: 1998, "JPL Planetary and Lunar Ephemerides,
DE405/LE405",JPL IOM 312.F-98-048.
[the preceeding 2 references are available in PostScript on the
following website: http://ssd.jpl.nasa.gov/iau-comm4/relateds.html]
******************************************************************************
SOFTWARE DESCRIPTION
--------------------
The software package (apart from the programs used to initially construct the
ephemeris, asc2eph, binmerge, and binshort) consists of a main test program
which uses the reading and interpolating routines in order to retrieve the
ephemeris data and to compare the results against the Test Data.
Two of the subroutines called by testeph.f are of primary interest to the user:
"PLEPH" and "SELCON". Three others, "CONST", "DPLEPH", and "STATE" may also be
useful.
PLEPH : Get the state vector (position and velocity) of one body with
respect to another at any given time within the interval covered
by the ephemeris.
SELCON : Retrieve values of user-requested constants on the ephemeris file.
CONST : Retrieve values of all of the constants on the ephemeris file.
DPLEPH : Same as PLEPH, but with increased precision in the input time.
STATE : Read and interpolate the ephemeris file. (Called by PLEPH).
******************************************************************************
SOFTWARE USAGE
--------------
C NOTE : Over the years, different versions of PLEPH have had a 5th argument:
C sometimes, an error return statement number; sometimes, a logical denoting
C whether or not the requested date is covered by the ephemeris. We apologize
C for this inconsistency; in this version, we use only the four necessary
C arguments and do the testing outside of the subroutine.
** PLEPH ******** subroutine pleph( tdb, npl, nctr, pv) **********
Input
-----
tdb [d.p.] : julian ephemeris date
npl [int.] : planet number
nctr [int.] : center number
identifications for "npl" and "nctr"
------------------------------------
1 = mercury 8 = neptune
2 = venus 9 = pluto
3 = earth 10 = moon
4 = mars 11 = sun
5 = jupiter 12 = solar-system barycenter
6 = saturn 13 = earth-moon barycenter
7 = uranus 14 = nutations in longitude and obliuity
15 = librations (if they exist on the file)
(for nutations and librations, nctr=0)
Output
------
pv(6) [d.p.] : x,y,z,x-dot,y-dot,z-dot [au, au/day]
for nutations, d(psi), d(eps), d(psi)-dot, d(eps)-dot
[rads, rads/day]
for librations, (Euler angles and rates, w.r.t. the ephemeris
reference frame) [rads, rads/day]
** SELCON ******** subroutine selcon ( nams, nmbr, vals) **********
Input
-----
nams(nmbr) [char*6] : names for which values are requested (the list of
names is given below)
nmbr [int.] : the number of names in 'nams'
Output
------
vals(nmbr) [d.p.] : values corresponding to the names in 'nams'
** CONST ******** subroutine const(nmv,vlv,sss,nrv) **********
Input (none)
-----
Output
------
nmv(nrv) [char*6] : list of nrv names associated with the values in vlv
vlv(nrv) [d.p.] : nrv values associated with the names in nmcc
sss(3) [d.p.] :
sss(1) : starting jed of the ephemeris file
sss(2) : ending jed of the ephemeris file
sss(3) : number of days covered by each block
of Chebychev coefficients
nrv [int.] : number of values in nmv and vlv
** STATE ******** subroutine state(jed,list,pv,nut,*) **********
[This subroutine is identical to that provided in the past; it is still
provided to give previous users compatability; it is not recommended for
use by first-time users.]
** DPLEPH ******** entry dpleph( tdb2, npl, nctr, pv) **********
This entry is identical to "PLEPH", except that the input time, tdb2, is
doubly-dimensioned for increased precision [ double precision tdb2(2) ].
Any combination of tdb2(1)+tdb2(2) which falls within
the time span on the file is a permissible epoch.
For ease in programming, the user may put the entire
date into tdb2(1) and set tdb2(2)=0.
However, for maximum interpolation accuracy, set
tdb2(1) equal to the most recent midnight at or
before interpolation epoch (i.e., xxxxxxx.5d0) and
set tdb2(2) equal to the remaining fractional part
of the day.
As an alternative, it may prove convenient to set
tdb2(1) equal to some fixed epoch, such as start of
integration, and set tdb2(2) equal to the remainder
of the desired epoch.
******************************************************************************
CONSTANTS ON THE EPHEMERIS FILE
-------------------------------
The following is a partial list of constants found on the ephemeris file:
DENUM Planetary ephemeris number.
LENUM Lunar ephemeris number.
TDATEF, TDATEB Dates of the Forward and Backward Integrations
CLIGHT Speed of light (km/s).
AU Number of kilometers per astronomical unit.
EMRAT Earth-Moon mass ratio.
GMi GM for ith planet [au**3/day**2].
GMB GM for the Earth-Moon Barycenter [au**3/day**2].
GMS Sun (= k**2) [au**3/day**2].
X1, ..., ZD9 Initial conditions for the numerical integration,
given at "JDEPOC", with respect to "CENTER".
JDEPOC Epoch (JED) of initial conditions, normally JED 2440400.5.
CENTER Reference center for the initial conditions.
(Sun: 11, Solar System Barycenter: 12)
RADi Radius of ith planet [km].
MA0001...MA0324 GM's of asteroid number 0001 ... 0234 [au**3/day**2].
PHASE The phase angle of the moon's rotation.
LOVENO The Love Number, k2, for the moon.
PHI, THT, PSI Euler angles of the orientation of the lunar mantle.
OMEGAX, ... Rotational velocities of the lunar mantle.
PHIC,THTC,PSIC Euler angles of the orientation of the lunar core.
OMGCX, ... Rotational velocities of the lunar core.
******************************************************************************
ASSISTANCE
----------
If you are really stuck, direct your questions to
*********************************************************
* William Folkner; JPL m/s 301-150; Pasadena, CA 91109 *
* TEL: 818-354-0443 FAX: 818-393-7631 *
* e-mail: William.Folkner@jpl.nasa.gov *
*********************************************************
Please include your name, address, phone number and e-mail address.
===============================================================================
APPENDIX A : The internal format of the ephemeris files
On the first record of an export binary file or in the "GROUP 1050 of the ascii
"header", there are 3 sets of 13 integers each. (In the binary version, the
13th of each set is stored away from the first 12.)
The 13 triplets give information about the location, order and time-coverage of
the chebychev polynomials corresponding to the following 13 items:
Mercury
Venus
Earth-Moon barycenter
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Moon (geocentric)
Sun
Nutations
Librations
Word (1,i) is the starting location in each data record of the chebychev
coefficients belonging to the ith item. Word (2,i) is the number of chebychev
coefficients per component of the ith item, and Word (3,i) is the number of
complete sets of coefficients in each data record for the ith item.
Data Records ("GROUP 1070")
These records contain the actual ephemeris data in the form of chebychev
polynomials.
The first two double precision words in each data record contain
Julian date of earliest data in record.
Julian date of latest data in record.
The remaining data are chebychev position coefficients for each component of
each body on the tape. The chebychev coefficients for the planets represent
the solar system barycentric positions of the centers of the planetary systems.
There are three cartesian components (x, y, z), for each of the items #1-11;
there are two components for the 12th item, nutations : d(psi) and d(epsilon);
there are three components for the 13th item, librations : three euler angles.
Planetary positions are given in kilometers. DE200 is nominally with respect
to the mean equator and equinox of J2000, coinciding with the origin of FK5;
DE403 and DE405 are with respect to the Int Cel Ref Frame. The nutations and
librations are given in radians.
===============================================================================
APPENDIX B : CDrom available from Willmann-Bell
The CD's containing DE200 and DE405 (unix and ascii) and also DE406 (unix only)
are available from Willmann-Bell. The price is about $25 per disk.
Willmann-Bell, Inc.
PO Box 35025
Richmond, VA 23235
804-320-7016
804-272-5920 (Fax)
http://www.willbell.com/software/jpl.htm
There is an order form that calculates all costs to any country in the world
on their web page (www.willbell.com). On the home page there is an icon for
this. The order form activates security for credit card transactions. If one
does not want to order over the web, one can print the order form and fax or
mail it to them.
===============================================================================
APPENDIX C : Corrections to the software on the CDroms
The enclosed are improvements to the software on the CDroms.
(The ftp software on "ssd.jpl.nasa.gov" has been updated.)
1) In "testeph.f" on both CDroms, line 95 should now be
INTEGER LINE/0/
2) In "testeph.f" on both CDroms, the statement at line 142 was
DEL=DABS(R(NCOORD)-XI)/(DABS(R(NCOORD))+DABS(XI))
it should be replaced by:
DEL=DABS(R(NCOORD)-XI)
if(ntarg .eq. 15 .and. ncoord .eq. 3)
* del=del/(0.23d0*(et-2451545.d0))
3) In "testeph.f" on both CDroms, the statement that was
at line 446 should now be
IF(FIRST) CALL STATE(0.D0,0,0,0.D0)
4) In "asc2eph.f" on both CDroms, the statement near line 190 was
READ (*,'(2I6,3000(/3D26.18))',IOSTAT =IN)
. NRW, NCOEFF, (DB(K),K=1,NCOEFF)
it should replaced by:
1 READ(*,'(2i6)')NRW,NCOEFF
if(NRW .EQ. 0) GO TO 1
READ (*,'(3D26.18)',IOSTAT =IN) (DB(K),K=1,NCOEFF)
5) In "asc2eph.f" ***>> on the DE406 ascii CDrom only <<*** :
"3D26.18" in line 268 should be replaced by "3D23.15"
6) In "asc2eph.f" on both CDroms, the 4th from last line was
READ (*, '(A)') BLANK
it should now be:
IF(HEADER .NE. 'GROUP 1070') READ (*, '(A)') BLANK
===============================================================================
APPENDIX D : Documentation of DE405 and DE406
DE405 Documentation is available from the anonymous ftp site,
"ssd.jpl.nasa.gov", in the directory, "/disk/ftp/pub/eph/export/ascii/",
The memo is in two forms:
1) in a single complete PostScript file, "de405iom.ps", or in
2) LaTeX file, "de405iom.tex" with the accompanying figures,
"de405fig1.ps", ... "de405fig8.ps".
The memo for DE403 remains in the directory, "/pub/eph/planets/de403.iom/":
"de403iom.tex" along with the separate figures, "fig1.ps", ... "fig9.ps".
===============================================================================
Appendix E : Versions of the software in various languages (from outside sources)
There are a number of contributed versions of the reading routines in
various languages; there are also ephemeris toolkits, binary file
conversions, etc. These are simply listed here; I have not tested
them.
All responsibility for these software packages resides with their
authors, and all questions pertaining to their use must be directed to
the authors themselves.
C-Versions
----------
From Paul Hardy : http://www.ephemeris.com/software.html
The ephemeris.com Software Library, designed to read, write, and
interpolate NASA's JPL ephemeris files (DE200, DE405, DE406, etc.) is
now available online at
http://www.ephemeris.com/software.html
The software includes standalone programs to read and write ASCII and
binary ephemeris files, interpolate positions, and verify calculations
with pre-computed data from JPL. The accuracy should match the
accuracy of JPL's software. The software is written in C, and should
work on any Unix machine. It will probably run on any other computer
that has the Gnu C compiler.
This software is designed to directly read the binary and ASCII
ephemeris files on JPL's ephemeris CD (available from
http://www.willbell.com), regardless of the machine's byte ordering.
-----------------
From Kourosh Arfa-Kaboodvand, Technical University of Darmstadt:
(Kourosh@ipgs.ipg.verm.tu-darmstadt.de)
/ftp/pub/ephem/export/C-versions/kourosh
From David Hoffman, Johnson Space Center (david.a.hoffman1@jsc.nasa.gov):
/ftp/pub/ephem/export/C-versions/hoffman
-----------------
From Dr. Piotr Dybczynski, Astronomical Observatory, Poznan, Poland
(dybol@phys.amu.edu.pl)
/ftp.astro.amu.edu.pl, IP: 150.254.66.60
FITS-version
------------
From Arnold Rots of Harvard-Smithsonian Astrophysical Observatory
(arots@head-cfa.harvard.edu)
ftp://heasarc.gsfc.nasa.gov/xte/calib_data/clock/bary
Python version
--------------
From Ray Buvel
rbuvel@wi.rr.com
Matlab-Based JPL Solar System Ephemeris Toolbox
-----------------------------------------------
From Brian Sauser at Kennedy Space Center (brian.sauser-1@ksc.nasa.gov)
http://technology.ksc.nasa.gov
UNIX - LINUX Binary Format Conversion
-------------------------------------
From Thierry Pauwels, Royal Observatory of Belgium:
Thierry.Pauwels@oma.be
===============================================================================
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