  In a recent paper published in Classical and Quantum Gravity, 2004, vol. 21,
p. 3803 Carlip used a vector-tensor theory of gravity to calculate the Shapiro
time delay by a moving gravitational lens. He claimed that the relativistic
correction of the order of v/c beyond the static part of the Shapiro delay
depends on the speed of light c and, hence, the Fomalont-Kopeikin experiment is
not sensitive to the speed of gravity c_g. In this letter we analyze Carlip's
calculation and demonstrate that it implies a gravitodynamic (non-metric)
system of units based on the principle of the constancy of the speed of gravity
but it is disconnected from the practical method of measurement of astronomical
distances based on the principle of the constancy of the speed of light and the
SI metric (electrodynamic) system of units. Re-adjustment of
theoretically-admissible but practically unmeasurable Carlip's coordinates to
the SI metric system of units used in JPL ephemeris, reveals that the
velocity-dependent correction to the static part of the Shapiro time delay does
depend on the speed of gravity c_g as shown by Kopeikin in Classical and
Quantum Gravity, 2004, vol. 21, p. 1. This analysis elucidates the importance
of employing the metric system of units for physically meaningful
interpretation of gravitational experiments.
