Coordinate transformations

cart2geo(xyz[, ecc2, R_eq, n_iters])	Transform Cartesian coordinates into geodetic coordinates.
geo2cart(geo[, ecc2, R_eq])	Transform geodetic coordinates into Cartesian coordinates.
rot_fk5j2000_icrs(xyz)	Rotation from FK5 to ICRS.
rot_icrs_fk5j2000(xyz)	Rotation from ICRS to FK5.
rot_itrs_icrs(xyz[, time_expr, thresh, eop_data])	Rotation from ITRS to ICRS.
rot_icrs_itrs(xyz[, time_expr, thresh, eop_data])	Rotation from ICRS to ITRS.