Precessing Jet in the High-Redshift Blazar J0017+8135
  The prominent flat-spectrum radio quasar J0017+8135 (S5 0014+81) at z = 3.366
is one of the most luminous active galactic nuclei (AGN) known. Its
milliarcsecond-scale radio jet structure has been studied with very long
baseline interferometry (VLBI) since the 1980s. The quasar was selected as one
of the original defining objects of the International Celestial Reference
Frame, but left out from its current second realization (ICRF2) because of
systematic long-term positional variations. Here we analyse archival 8.6- and
2.3-GHz VLBI imaging data collected at nearly 100 different epochs during more
than 20 years, to obtain information about the kinematics of jet components.
Because of the cosmological time dilation, extensive VLBI monitoring data are
essential to reveal changes in the jet structure of high-redshift AGN. In the
case of J0017+8135, the data can be described with a simple kinematic model of
jet precession with a 12-year periodicity in the observer's frame.
