Like the Lunar Ephemeris, The AGC uses the position of the Sun to for orbital integration. Given the relatively small movement of the sun with respect to the moon the computation simplified.
Form of the Ephemeris
The solar ephemeris is defined by three parameters. First the positional state vectors of the sun with respect to the earth at TIMEMO, the ephemeris time. Second, the velocity vector of the sun relative to the earth at TIMEMO. Last, the angular velocity of the position vector.