Function lupnt::GetIauSofaData

• Defined in File iau_sofa.cc

Function Documentation

IauSofaData lupnt::GetIauSofaData(Real jd_tt)

Interpolate the CIP coordinates (X, Y) and CIO locator (s) to a requested epoch from the loaded IAU SOFA series table.

Called by RotPrecessionNutation (frame_conversions.cc) to build the IAU 2006/2000A precession-nutation rotation matrix used throughout GCRF<->ITRF frame conversions (GcrfToItrf/ItrfToGcrf). Lazily loads the bundled table via LoadIauSofaFileData on first use. For epochs outside the table’s range, the nearest endpoint’s values are held constant; otherwise a 9th-order Lagrange interpolation is used.

Parameters:

jd_tt – Epoch at which to evaluate the series [Julian Date, TT]

Returns:

Interpolated CIP coordinates and CIO locator, X/Y/s [arcsec] (multiply by RAD_ARCSEC to convert to radians, as done in RotPrecessionNutation)