Analytical theories and models

iau2006([time_expr, thresh])	IAU2000/2006 precession-nutation theory.
egm2008_pot(xyz, n, m[, mu, a])	Geopotential (EGM2008).
egm2008_acc(xyz, n, m[, mu, a])	Gravitational acceleration (EGM2008).
get_egm2008_mu()	Get the gravitational parameter of the EGM2008 model.
get_egm2008_a()	Get Earth's reference radius in the EGM2008 model.
vsop2013_cartesian_icrf(pl_idx[, time_expr, ...])	Get the VSOP2013 formulae (ICRS Cartesian state).
vsop2013_cartesian(pl_idx[, time_expr, thresh])	Get the VSOP2013 formulae (Cartesian state).
vsop2013_elliptic(pl_idx[, var_idx, ...])	Get the VSOP2013 formulae (elliptic orbital elements).
get_vsop2013_mus()	Get the gravitational parameters of the VSOP2013 theory.
elp2000_cartesian_fk5([time_expr, thresh])	Get the ELP2000 formulae (FK5 J2000 frame).
elp2000_cartesian_e2000([time_expr, thresh])	Get the ELP2000 formulae (inertial mean ecliptic and equinox of J2000).
get_elp2000_mus()	Get the gravitational parameters of the ELP2000 theory.