Earth orientation and space weather

era([time_expr, eop_data])	Earth rotation angle.
erap([time_expr, eop_data])	Derivative of the Earth rotation angle.
gmst82([time_expr, eop_data])	Greenwich mean sidereal time (IAU 1982 model).
gmst82p([time_expr, eop_data])	Derivative of the Greenwich mean sidereal time (IAU 1982 model).
pm_x([time_expr, eop_data])	Polar motion (x component).
pm_xp([time_expr, eop_data])	Derivative of the polar motion (x component).
pm_y([time_expr, eop_data])	Polar motion (y component).
pm_yp([time_expr, eop_data])	Derivative of the polar motion (y component).
dX([time_expr, eop_data])	Correction to the Earth's precession/nutation model (x component).
dXp([time_expr, eop_data])	Derivative of the correction to the Earth's precession/nutation model (x component).
dY([time_expr, eop_data])	Correction to the Earth's precession/nutation model (y component).
dYp([time_expr, eop_data])	Derivative of the correction to the Earth's precession/nutation model (y component).
Ap_avg([time_expr, sw_data])	Average of the geomagnetic Ap indices.
f107([time_expr, sw_data])	Observed 10.7-cm solar radio flux.
f107a_center81([time_expr, sw_data])	Average of the 10.7-cm solar radio flux.