By executing the following programmes on your computer, obtain data from hpiers server.

The Windows programmes only work in the command line mode (with the msdos windows).

1- Earth orientation parameters from civil date (combined series C04 - click here for description)

Address of the webservice server : http://hpiers.obspm.fr/eop-pc/webservice/server_EOP2.php

Example of a php client calling this webservice :

Getting the php client source : http://hpiers.obspm.fr/eop-pc/webservice/files/client_EOP2_php.txt
Inputs : date (YYYY MM DD)
Outputs :MJDxyUT1-UTCLODdXdYx Erry ErrUT1-UTC ErrLod ErrdY ErrdY Err
Executable for Windows : DOWNLOAD
Executable for Linux : DOWNLOAD

2- Earth Orientation Matrix at a given instant - see also

Address of the webservice server :


Example of a php client calling this webservice :

Getting the php client source : http://hpiers.obspm.fr/eop-pc/webservice/files/client_MATRICE_EOP_php.txt
Inputs: year month day hour minute seconde polar motion nutation diurnal/semi-diurnal tides.
(YYYY) (MM) (DD) (0-23) (0-59) (0-59) (0 or 1) (0 or 1) (0 or 1)

  Outputs : Element of the Earth Orientation Matrix a11, a12, a13, a21, a22, a23, a31, a32, a33

Executable for Windows : DOWNLOAD
Executable for Linux : DOWNLOAD

Transformation coordinate M from the international terrestrial reference system (ITRF) to the international celestial reference frame (ICRF) :

Celestial coordinates ( X Y Z) = M x Terrestrial coordinates ( x y z )

We use the FORTRAN CODE of the VLBI analysis Software GLORIA developped by Anne-Marie Gontier (Paris Observatory), and compatible with the IAU 2000 resolutions

  • from 1962 to the current week the matrix can include the whole EOP set of the IERS combined series C04 (daily step, 0hUTC, time resolution for such EOP fluctuations is about 6 days), as well as diurnal and semi-diurnal effects produced by ocean tides, which amount about 0.001". Accuracy is 0.0001", corresponding to 5 10-10 rad. In turn the time resolution of the matrix can reach approximatively 6 hours. Bewteen two dates at 0hUTC the EOP are interpolated according to a cubic spline.

  • from the current week to 6 months after the matrix is computed from the prediction of the polar motion and UT1-UTC.

  • outside the range [1962, current week+ 6 months prediction] the rotation matrix is restricted to the diurnal rotation and the precession-nutation model IAU 2000.

  • The last digit (12) of the matrix element corresponds to the pico radian level. Corresponding time resolution for the matrix variation is 14 nano seconds.

  • Components of the instantaneous rotation vector are deduced from the orientation matrix and its time derivative.