astroforge.coordinates.ITRSToTIRS

astroforge.coordinates.ITRSToTIRS(mjd, X)

Rotate a cartesian vector from the International Terrestrial Reference System (ITRS) to the Terrestrial Intermediate Reference System(TIRS) coordinate system. TIRS differs from ITRS by the polar motion. See Kaplan (2005) for more information.

Parameters:

• time (float) – Time at which to evaluate the polar motion, specified as Modified Julian Date (MJD), in the UT1 time system.

• X (NDArray[np.float64]) – Shape (3,) cartesian vector to be rotated from ITRS to TIRS

Returns:

Rotated vector

Return type:

NDArray[np.float64]