IMCCE CNRS Observatoire de la Côte d'Azur SYRTE
Download INPOP17a

Mailing list

In order to be informed of further evolution of the INPOP ephemerides, please send an email of interest to inpop@imcce.fr


File format

These INPOP17a ephemeris files are provided in four file formats


Binary files

These INPOP17a ephemeris files extend the internal format of the binary JPL DExxx ephemeris files (http://ssd.jpl.nasa.gov/?ephemerides) by including the time scale transformation TT-TDB or TCB-TCG. These binary files are encoded using the "INPOP binary ephemeris file format - version 2.0". These files provide the orbital solution expressed in the TDB and TCB time scale. The coordinates in the data files are expressed as the coefficients of the Chebychev polynomials. These INPOP17a ephemeris files don't include the coefficients for the nutation.

Usage

These files can't be read using the older programs based on the "testeph.f" program. These files must be read with the CALCEPH Library which provides a compatible C and Fortran Application Programming Interface.

Binary files including the time scale transformation TT-TDB or TCG-TCB - release INPOP17a

time period
(years from J2000)
TDB time scale TCB time scale
-100 to +100 binary file (18 Mbytes)
binary file (18 Mbytes)
-1000 to +1000 binary file (178 Mbytes) binary file (178 Mbytes)


Text files

These INPOP13 ephemeris files are encoded as plain text files : the coordinates in the ascii data files are expressed as the coefficients of the Chebychev polynomials. These files provide the orbital solution expressed in the TDB and TCB time scale. These files don't include the coefficients for the nutation but they include the time scale transformation TT-TDB or TCG-TCB.
The file format of these files are described in the following document. The exponent letter of the real numbers is 'D' (instead of 'E').

The ascii testpo files are provided to check that your software is able to read the files and return the correct values. The testpo files use the same format as the JPL program testeph.f.

Text files including the time scale transformation TT-TDB or TCG-TCB - release INPOP17a

time period
(years from J2000)
TDB time scale TCB time scale
-100 to +100 binary file (64 Mbytes) binary file (64 Mbytes)
-1000 to +1000 binary file (642 Mbytes) binary file (642 Mbytes)


SPICE data files

These INPOP17a ephemeris files uses the internal format of the SPICE data files (kernels) (http://naif.jpl.nasa.gov/naif/). These files provide the orbital solution expressed only in the TDB time scale. The coordinates in the data files are expressed as the coefficients of the Chebychev polynomials. These files don't include the coefficients for the nutation but they include the time scale transformation TT-TDB.

Usage

These files could be read using the CALCEPH Library, which provides a compatible C and Fortran Application Programming Interface, or with the SPICE toolkit library. The CALCEPH Library allow to access to the multiple ephemeris files at the same time.

SPICE data files - release INPOP17a

time period
(years from J2000)
TDB time scale
-100 to +100 binary file (18 Mbytes)
-1000 to +1000 binary file (178 Mbytes)


Binary files compatible with the JPL DExxx ephemeris file format (without the time scale transformation TT-TDB or TCG-TCB)

These INPOP17a ephemeris files use the same internal format as the binary JPL DExxx ephemeris files (http://ssd.jpl.nasa.gov/?ephemerides) : the coordinates in the data files are expressed as the coefficients of the Chebychev polynomials. These files provide the orbital solution expressed in the TDB and TCB time scale. These files don't include the coefficients for the nutation and the time scale transformation TT-TDB or TCG-TCB. So these files could be read with the same programs (such as the JPL software package) which read the binary JPL ephemeris files.
The internal format is described in the paper :
David Hoffman : 1998,
A Set of C Utility Programs for Processing JPL Ephemeris Data,
ftp://ssd.jpl.nasa.gov/pub/eph/export/C-versions/hoffman/EphemUtilVer0.1.tar

Due to the problem of the endianess in the computer (order in which integers are stored as bytes in computer memory), the binary files are available into two formats :

The ascii header files are provided to show the content of the two first records of the binary ephemeris files. The file format of these ascii files is the same as described in (Hoffman, 1998).

The ascii testpo files are provided to check that your software is able to read the files and return the correct values. The testpo files is compliant with the format requested by the JPL program testeph.f and could be used with it.

Usage

To use these data files instead of the JPL ephemeris files, you only have to change the name of the files in your software program.
If you use a program based on the "testeph.f" program from the JPL, then you may have to set the variable NRECL (and KSIZE if you don't use the subroutine FSIZER2). The prefered method is to read the beginning of the first record and then to compute the length of the records (same as KSIZE) with the libration's triplet (which contains the location, order and time-coverage of Chebychev polynomial).

We provide the open-source CALCEPH Library, which provides a compatible C and Fortran Application Programming Interface. This library avoids the problems with the variables (NRECL and KSIZE) and the endianess. It supports the access to the multiple ephemeris files at the same time.

Binary data files compatible with the JPL DExxx ephemeris file format - release INPOP17a

TDB time scale
time period
(years from J2000)
little-endian files
(Intel or AMD x86, x86_64 or IA64 processors)
big-endian files
(Motorola PowerPC, IBM Power or Sparc processors)
value of KSIZE
(for the program "testeph.f")
ascii header files
(for information)
testpo files
(for checking)
-100 to +100 binary file (17 Mbytes) binary file (17 Mbytes) 1876 ascii file ascii file
-1000 to +1000 binary file (168 Mbytes) binary file (168 Mbytes) 1876 ascii file ascii file
TCB time scale
time period
(years from J2000)
little-endian files
(Intel or AMD x86, x86_64 or IA64 processors)
big-endian files
(Motorola PowerPC, IBM Power or Sparc processors)
value of KSIZE
(for the program "testeph.f")
ascii header files
(for information)
testpo files
(for checking)
-100 to +100 binary file (17 Mbytes) binary file (17 Mbytes) 1876 ascii file ascii file
-1000 to +1000 binary file (168 Mbytes) binary file (168 Mbytes) 1876 ascii file ascii file

Contact

For all comments concerning these pages, contact the authors : inpop@imcce.fr.

Last revision : 07 September 2017


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