A possible jet precession in the periodic quasar B0605-085
  The quasar B0605-085 (OH 010) shows a hint for probable periodical
variability in the radio total flux-density light curves. We study the possible
periodicity of B0605-085 in the total flux-density, spectra and opacity changes
in order to compare it with jet kinematics on parsec scales. We have analyzed
archival total flux-density variability at ten frequencies (408 MHz, 4.8 GHz,
6.7 GHz, 8 GHz, 10.7 GHz, 14.5 GHz, 22 GHz, 37 GHz, 90 GHz, and 230 GHz)
together with the archival high-resolution very long baseline interferometry
data at 15 GHz from the MOJAVE monitoring campaign. Using the Fourier transform
and discrete autocorrelation methods we have searched for periods in the total
flux-density light curves. In addition, spectral evolution and changes of the
opacity have been analyzed. We found a period in multi-frequency total
flux-density light curves of 7.9+-0.5 yrs. Moreover, a quasi-stationary jet
component C1 follows a prominent helical path on a similar time scale of 8
years. We have also found that the average instantaneous speeds of the jet
components show a clear helical pattern along the jet with a characteristic
scale of 3 mas. Taking into account average speeds of jet components, this
scale corresponds to a time scale of about 7.7 years. Jet precession can
explain the helical path of the quasi-stationary jet component C1 and the
periodical modulation of the total flux-density light curves. We have fitted a
precession model to the trajectory of the jet component C1, with a viewing
angle phi=2.6+-2.2 degrees, aperture angle of the precession cone
Omega=23.9+-1.9 degrees and fixed precession period (in the observers frame) P
= 7.9 yrs.
