  High-precision astrometry on sub-micro-arcsecond level in angular resolution
requires accurate determination of the trajectory of a light-signal from the
celestial light source through the gravitational field of the Solar system
toward the observer. In this investigation the light trajectory in the
gravitational field of N moving bodies is determined in the 1.5 post-Newtonian
approximation. In the approach presented two specific issues of particular
importance are accounted for:
  (1) According to the recommendations of International Astronomical Union, the
metric of the Solar system is expressed in terms of intrinsic mass-multipoles
and intrinsic spin-multipoles of the massive bodies, allowing for arbitrary
shape, inner structure and rotational motion of the massive bodies of the Solar
system.
  (2) The Solar system bodies move along arbitrary worldlines which can later
be specified by Solar system ephemeris.
  The presented analytical solution for light trajectory is a primary
requirement for extremely high-precision astrometry on sub-micro-arcsecond
level of accuracy and associated massive computations in astrometric data
reduction. An estimation of the numerical magnitude for time delay and light
deflection of the leading multipoles is given.
