Jet Kinematics of the Quasar 4C +21.35 from Observations with the KaVA
  Very Long Baseline Interferometry Array
  We present the jet kinematics of the flat spectrum radio quasar (FSRQ) 4C
+21.35 using time-resolved KaVA very long baseline interferometry array radio
maps obtained from September 2014 to July 2016. During two out of three
observing campaigns, observations were performed bi-weekly at 22 and 43 GHz
quasi-simultaneously. At 22 GHz, we identified three jet components near the
core with apparent speeds up to (14.4+/-2.1)c. The timing of the ejection of a
new component detected in 2016 is consistent with a gamma-ray flare in November
2014. At 43 GHz, we found four inner jet (<3 mas) components with speeds from
(3.5+/-1.4)c to (6.8+/-1.5)c. Jet component speeds tend to be higher with
increasing distances from the core. We compared our data with archival Very
Long Baseline Array (VLBA) data from the Boston University (BU) 43 GHz and the
Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE)
15.4 GHz monitoring programs. Whereas MOJAVE data and our data are in good
agreement, jet speeds obtained from the BU Program data in the same time period
are about twice as high as the ones we obtain from the KaVA data. The
discrepancy at 43 GHz indicates that radio arrays with different angular
resolution identify and trace different jet features even when the data are
obtained at the same frequency and at the same time. The flux densities of jet
components decay exponentially, in agreement with a synchrotron cooling time
scale of about 1 year. Using known electron Lorentz factor values (about
9,000), we estimate the magnetic field strength to be around 1-3 micro-Tesla.
When adopting a jet viewing angle of 5 degrees, the intrinsic jet speed is of
order 0.99c.
