  The most precise test of the post-Newtonian gamma parameter in the solar
system has been achieved in measurement of the frequency shift of radio waves
to and from the Cassini spacecraft as they passed near the Sun. The test relies
upon the JPL model of radiowave propagation that includes, but does not
explicitly parametrize, the impact of the non-stationary component of the
gravitational field of the Sun, generated by its barycentric orbital motion, on
the Shapiro delay. This non-stationary gravitational field of the Sun is
associated with the Lorentz transformation of the metric tensor and the affine
connection from the heliocentric to the barycentric frame of the solar system
and can be treated as gravimagnetic field.
  The gravimagnetic field perturbs the propagation of a radio wave and
contributes to its frequency shift at the level up to 4 10^{-13} that may
affect the precise measurement of the parameter gamma in the Cassini experiment
to about one part in 10,000. Our analysis suggests that the translational
gravimagnetic field of the Sun can be extracted from the Cassini data, and its
effect is separable from the space curvature characterized by the parameter
gamma.
