A v _ { J } / c correction to the Shapiro time delay seems verified by a 2002 Jovian observation by VLBI .
In this Essay , this correction is interpreted as an effect of the aberration of light in an optically refractive medium which supplies an analog of Jupiter ’ s gravity field rather than as a measurement of the speed of gravity , as it was first proposed by other authors .
The variation of the index of refraction is induced by the Lorentz invariance of the weak gravitational field equations for Jupiter in a uniform translational slow motion with velocity v _ { J } = 13.5 km / s .
The correction on time delay and deflection is due not to the Kerr ( or Lense-Thirring ) stationary gravitomagnetic field of Jupiter , but to its Schwarzschild gravitostatic field when measured from the barycenter of the solar system .