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^{10 }rad.
 from the
current week to 6 months afterthe matrix
is computed from the prediction of the polar motion and UT1UTC.
 outside the range
[1962, current week+ 6 months prediction]
the rotation matrix is restricted to the diurnal rotation and the precessionnutation
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.
