by Standish, et. al.
$24.95
The JPL Planetary and Lunar Ephemerides on CD-ROM
contains three different Jet Propulsion Laboratory Planetary and Lunar
Ephemerides (DE200, DE405, and DE406) along with associated reading and interpolating
routines. These allow a competent user to obtain the rectangular coordinates of the sun,
moon, and nine major planets by means of a subroutine written in standard FORTRAN. The
data and programs should be viewed by the potential user as a "tool box" for one
skilled in computer programming and knowledgeable about astronomical computing.
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).
DE405 : (includes both nutations and librations)
JED 2305424.50 (1599 DEC 09) to JED 2525008.50 (2201 FEB 20)
The latest JPL ephemeris, created in May-June, 1997. DE405 is based upon the International Celestial Reference Frame (ICRF), the newly-adopted reference frame of the International Astronomical Union (IAU). The frames of DE200 and DE405 differ by no more than about 0.01 arcseconds.
DE406 : the New "JPL Long Ephemeris" (includes neither nutations nor librations)
JED 0625360.50 (-3000 FEB 23) to 2816912.50 (+3000 MAY 06)
DE406 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.
The following is additional information from the read me files contained on the CD-ROM itself:
JPL PLANETARY AND LUNAR EPHEMERIDES
E M Standish, JPL
Copyright 1997, The Jet Propulsion Laboratory, California Institute of
Technology, All Rights Reserved.
Published by Willmann-Bell, Inc., P.O. Box 35025, Richmond, VA 23235.
The programs and data provided in this CD-ROM are based upon on a long-term and
ongoing scientific program of analysis and refinement. What is presented here
has been tested with care but is not guaranteed for any particular purpose.
Neither The Jet Propulsion Laboratory nor Willmann-Bell, Inc. offer any
warranties or representations, nor do they accept any liabilities with respect
to the contents of this CD-ROM.
============================== I. Introduction ==============================
This CD contains JPL Planetary and Lunar Ephemerides along with associated
reading and interpolating routines. These allow a competent user to obtain
the rectangular coordinates of the sun, moon, and nine major planets by means
of a subroutine written in standard fortran.
We suggest for the more casual user, JPL's interactive "telnet" site,
"Horizons", which provides a wide variety of astronomical information and
which uses the full precision of our ephemerides. See Section X.
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:
I. Introduction
II. How to Proceed
III. Brief Description of Items on the CD
IV. Available Ephemerides
V. Software Description
VI. Software Usage
VII. Constants on the Ephemeris File
VIII. Documentation and References
IX. C-Versions of the Software
X. Horizons - JPL's Interactive Ephemeris System
XI. Format of the Ephemeris Files
XII. Assistance
============================ II. How to Proceed ===========================
There are two different paths:
For UNIX-based users,
the actual ephemeris files are available in binary form, ready for immediate
installation on the user's computer or for use directly from the CD itself.
For all NON-UNIX-based users,
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. (Sorry, we have tried to export binary files for other
types of platforms, but the lack of uniformity from one computer and/or
compiler to the next made this too difficult.)
Therefore, the non-UNIX-based user, using the program "ASC2EPH", must create
a binary file by combining the desired choices of "ascSYYYY.XXX" preceded by
the proper corresponding "HEADER.XXX".
ALL USERS,
must tailor the program "TESTEPH" according to the instructions in
"USRGUIDE", paying attention to the parts about "NRECL" and "FSIZER".
Run "TESTEPH" as described in "USRGUIDE".
If "TESTEPH" works, you are done: "TESTEPH" uses the subroutines of interest
(which are described in Sections V and VI).
=================== III. Brief Description of Items on the CD ==============
"USRGUIDE" : User's Guide containing instructions for obtaining and/or
creating the binary direct-read ephemeris file, tailoring the
software, and testing the software package.
"TESTEPH" : The main program which uses, and therefore tests, 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.XXX" : Test results computed at JPL using the ephemeris DEXXX.
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
--------------
"unix.XXX" : The full binary ephemeris file of JPL Ephemeris DEXXX.
The file may be used straight from the CDrom by the
program "testeph", or it may be copied onto a hard disk.
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 (described in "USRGUIDE").
"ascSYYYY.XXX" : ASCII ephemeris files from JPL Ephemeris DEXXX, covering 20
years, starting in the year SYYYY (where "S" is "m" or "p",
indicating "-" or "+"; i.e., for "BC" or "AD"). The 20-year
blocks may be converted separately into binary ephemeris
files using "ASC2EPH", or they may be combined into a single
ASCII file 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 info for ephemeris deXXX, needed by "ASC2EPH.F".
======================= IV. 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).
DE405 : (includes both nutations and librations)
JED 2305424.50 (1599 DEC 09) to JED 2525008.50 (2201 FEB 20)
Our latest ephemeris, created in May-June, 1997. DE405 is based upon the
International Celestial Reference Frame (ICRF), the newly-adopted reference
frame of the International Astronomical Union (IAU). The frames of DE200
and DE405 differ by no more than about 0.01 arcseconds.
DE406 : the New "JPL Long Ephemeris" (includes neither nutations nor librations)
JED 0625360.50 (-3000 FEB 23) to 2816912.50 (+3000 MAY 06)
DE406 is the same ephemeris as DE405, though the accuracy of the interp-
olating 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.
Ephemeris items de200 de405 de406
--------------- ------ ------ -------
UNIX binary : 55 Mb 62 Mb 199 Mb
ASCII (each 20-year block) : 5.2 Mb 6.4 Mb
========================= V. 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
("TESTEPH") 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 contained in "TESTEPH" 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).
========================== VI. Software Usage ==============================
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 obliquity
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]
Note : Over the years, different versions of PLEPH have had a fifth argument:
sometimes, an error return statement number; othertimes, a logical denoting
whether or not the requested date is covered by the ephemeris. We apologize
for this inconsistency; in this version, we use only the four necessary
arguments and do the testing outside of the subroutine.
SELCON ******** subroutine SELCON ( nams, nmbr, vals) **********
Input
-----
nams(nmbr) [char*6] : names for which values are requested (a list of the
possible choices 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] : names of the constants used in creating the ephemeris
vlv(nrv) [d.p.] : values of the constants used in creating the ephemeris
nrv [int.] : number of names and values in nmv and vlv
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
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 compatibility; 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, and set tdb2(2) equal
to the time since that epoch.
====================== VII. 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 GM for the Sun (= k**2) [au**3/day**2].
X1, ..., ZD9 Initial conditions for the numerical integration,
given at "JDEPOC", with respect to "CENTER". [au and au/day]
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.
XL...ZDL Initial conditions of the libration angles.
===================== VIII. Documentation and References ====================
A copy of the JPL Inter Office Memorandum describing DE405 and DE406 is
available in TeX and the figures are available in Postscript, both available
at ftp://navigator.jpl.nasa.gov/pub/ephem/export/de405.iom/
and all 8 Postscript figures and the de405iom.ps file itself must be retrieved:
08/26/98 12:00AM 103,528 de405fig1.ps
08/26/98 12:00AM 107,870 de405fig2.ps
08/26/98 12:00AM 50,259 de405fig3.ps
08/26/98 12:00AM 46,775 de405fig4.ps
08/26/98 12:00AM 167,676 de405fig5.ps
08/26/98 12:00AM 47,201 de405fig6.ps
08/26/98 12:00AM 114,529 de405fig7.ps
08/26/98 12:00AM 110,497 de405fig8.ps
08/26/98 12:00AM 960,524 de405iom.ps
08/26/98 12:00AM 38,796 de405iom.tex
The following references also apply to the JPL Ephemerides:
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.
======================= IX. C-Versions of the Software ======================
There are C-versions of the software, written by outside users. Access to them
is described in the file, "/usr1/ftp/ephem/export/README";, on the anonymous ftp
site, ftp://navigator.jpl.nasa.gov/pub/ephem/export/C-versions/
And there are two subfolders to examine:
hoffman
kourosh
See the "README" file in the ftp://navigator.jpl.nasa.gov/pub/ephem/export/README for
details regarding external exportable user data for the JPL ephemeris progams.
======================= IX. C-Versions of the Software ======================
There are C-versions of the software, written by outside users. Access to them
is described in the file, "/usr1/ftp/ephem/export/README", on the anonymous ftp
site, "navigator.jpl.nasa.gov"]
============= X. Horizons : JPL's Interactive Ephemeris System ==============
Horizons, JPL's Interactive Ephemeris System, is now being made available as a
WWW site (July, 1997): http://ssd.jpl.nasa.gov
At present, the on-line ephemeris system is a telnet service. From a telnet-
capable machine, telnet to "ssd.jpl.nasa.gov 6775", where 6775 is a port. From
within a web-browser, such as Netscape, type "telnet://ssd.jpl.nasa.gov:6775".
The system will start automatically. No user-ID or password is required.
Reasons for being denied access are:
1) You typed the wrong machine address or port number.
2) The maximum allowed number of users are already connected. Try later.
3) The system is down (should be rare; 24/7 service is planned)
If a user-name/password is requested, you did not specify the port number.
The system will automatically negotiate the terminal type. If this fails
(common), the default will be a vt100 display.
The system will also attempt to determine your window size. If this fails
also common), it will default to a 24 row by 79 column screen display. If
this is inappropriate, and your display paging is choppy, manually set your
screen size by using the command "TTY {rows} {columns}", where {rows} and
{columns} are replaced by appropriate integers.
Address inquires concerning Horizons to : jon.giorgini@jpl.nasa.gov
==================== XI. Format of the Ephemeris Files ======================
It is not necessary to know the information contained in this section in order
to install and use the JPL ephemerides. Some users, however, have requested
parts of the following information, so it is provided here.
The first two records of the binary files contain header information; the rest
of the records contain the main ephemeris data. Each ephemeris data record
contains a block of 32 days (DE200 and DE405) or of 64 days (DE406) of
ephemeris polynomials.
For the ascii versions, the main ephemeris data come in 20-year pieces; each
piece is composed of a number of 32-day blocks or of 64-day blocks.
The first two words in each data record contain the JED of the beginning of the
data in the block and the JED of the ending of the data in the block.
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.
The roadmap to the contents of the 32-day or 64-day blocks is given by
"pointers", contained in the first record of the binary files or in the
"GROUP 1050" of the ascii headers. The pointers consist of 3 sets of 13
integers each. (In the binary version, the first 12 members of the three sets
are stored together; the 13th members of each set are stored later in the
record.) 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
For the ith item, pointer(1,i) is the starting location in each data record of
the chebychev coefficients; pointer(2,i) is the number of coefficients per
component; pointer(3,i) is the number of complete sets of coefficients in each
data record.
For example, the pointers for DE405 look like,
3 171 231 309 342 366 387 405 423 441 753 819 899
14 10 13 11 8 7 6 6 6 13 11 10 10
4 2 2 1 1 1 1 1 1 8 2 4 4
For the moon, starting in the 441st double precision word, there are 13
coefficients for the x-coordinate which apply over the first 4 (32/8) days of
the 32-day interval covered by this block of data. The next 13 coefficients
are for the y-coordinate; then, 13 for z. Seven similar sets follow for the
moon, making 13x3x8=312 words in all. The coefficients for the Sun follow
the moon, starting in the 753rd location.
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.
Velocites are obtained by interpolating the position polynomials.
Planetary positions are given in kilometers on the file, but are translated
automatically into AU's by the software unless overridden by the user. The
nutations and librations are given in radians.
DE200 is nominally with respect to the mean equator and equinox of J2000,
coinciding with the origin of FK5. DE405 is based upon the Intermational
Celestial Reference Frame (ICRF), the newly-adopted reference frame of the
International Astronomical Union (IAU). The frames of DE200 and DE405 differ
by no more than about 0.01 arcseconds.