matrice.php

Compute the Earth rotation matrix

                               2018 7 19     21 h 22 min 17 s   UTC 
                 
matrice:

-0.208697540126     0.977978619576     0.001776625412 
-0.977980174125    -0.208697815139    -0.000031224520 
 0.000340240928    -0.001744020910     0.999998421312

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 )

from 1962 to the current week the matrix can include the EOP of the IERS combined series C04 (time resolution for EOP fluctuations is about 6 days), as well as diurnal and semidiurnal variations in UT1 and polar motion produced by oceanic tides (IERS 2000 conventions). Accuracy is 0.0001", corresponding to 5 10^-10rad.
from the current week to 6 months afterthe 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.