 is well approximated by (V/C)**2, where V is the
      velocity of the target relative to an inertial frame and C is
      the speed of light.

      For nearly all objects in the solar system V is less than 60
      km/sec. The value of C is ~300000 km/sec. Thus the
      one-iteration solution for LT has a potential relative error
      of not more than 4e-8. This is a potential light time error of
      approximately 2e-5 seconds per astronomical unit of distance
      separating the observer and target