'Parameters
alpha_C, delta_C : float (deg) or `~astropy.units.Quantity`
Angles in the Celestial coordinate frame.
lon, lat, lon_pole : float (deg) or `~astropy.units.Quantity`
Parameter values when the model was initialized.
Returns
phi_N, theta_N : float (deg) or `~astropy.units.Quantity`
Angles on the Native sphere.'

def evaluate(self, alpha_C, delta_C, lon, lat, lon_pole):

    if isinstance(lon, u.Quantity):
        lon = lon.value
        lat = lat.value
        lon_pole = lon_pole.value
    phi = ((np.pi / 2) + lon)
    theta = ((np.pi / 2) - lat)
    psi = (- (lon_pole - (np.pi / 2)))
    (phi_N, theta_N) = super(RotateCelestial2Native, self)._evaluate(alpha_C, delta_C, phi, theta, psi)
    return (phi_N, theta_N)
