  The accuracy of astrometric observations conducted via a space-borne optical
interferometer orbiting the Earth is expected to approach a few
microarcseconds. Data processing of such extremely high-precision measurements
requires access to a rigorous relativistic model of light ray propagation
developed in the framework of General Relativity. The data-processing of the
space interferometric observations must rely upon the theory of
general-relativistic transformations between the spacecraft, geocentric, and
solar barycentric reference systems allowing unique and unambiguous
interpretation of the stellar aberration and parallax effects. On the other
hand, the algorithm must also include physically adequate treatment of the
relativistic effect of light deflection caused by the spherically-symmetric
(monopole-dependent) part of the gravitational field of the Sun and planets as
well as the quadrupole- and spin-dependent counterparts of it. In some
particular cases the gravitomagnetic field induced by the translational motion
of the Sun and planets should be also taken into account for unambigious
prediction of the light-ray deflection angle. In the present paper we describe
the corresponding software program for taking into account all classical
(proper motion, parallax, etc.) and relativistic (aberration, deflection of
light) effects up to the microarcsecond threshold and demonstrate, using
numerical simulations, how observations of stars and/or quasars conducted on
board a space optical interferometer orbiting the Earth can be processed and
disentangled.
