  Solving the null geodesic equations for a ray of light is a difficult task
even considering a stationary spacetime. The problem becomes even more
difficult if the electromagnetic signal propagates through a flowing optical
medium. Indeed, because of the interaction between light and matter, the signal
does not follow a null geodesic path of the spacetime metric anymore. However,
having a clear description of how the time and frequency transfers are affected
in this very situation is of a prime importance in astronomy. As a matter of
fact, ranging to satellites and Moon, very long baseline interferometry, global
navigation satellite systems, and radio occultation experiments are few
examples of techniques involving light propagation in flowing optical media. By
applying the time transfer functions formalism to optical spacetime, we show
that the time and frequency transfers can be determined iteratively up to any
desired order within the quasi-Minkowskian path approximation. We present some
applications in the context of radio occultation experiments and discuss
possible future applications to the modeling of tropospheric delays.
