Investigating the temporal domain of massive ionized jets - I. A pilot
  study
  We present sensitive ($\sigma<10{\rm \mu Jy \, beam^{-1}}$), radio continuum
observations using the Australian telescope compact array (ATCA) at frequencies
of $6$ and $9$ GHz towards 4 MYSOs. From a previous, less sensitive work, these
objects are known to harbour ionized jets associated with radio lobes, which
result from shock processes. In comparison with that work, further emission
components are detected towards each MYSO. These include extended, direct,
thermal emission from the ionized jet's stream, new radio lobes indicative of
shocks close ($<10^5\, {\rm au}$) to the MYSO, 3 radio Herbig-Haro objects
separated by up to $3.8 {\rm pc}$ from the jet's launching site and an IR-dark
source coincident with CH$_3$OH maser emission. No significant, integrated flux
variability is detected towards any jets or shocked lobes, and only one proper
motion is observed ($1806\pm596\,{\rm km \, s^{-1}}$ parallel to the jet axis
of G310.1420+00.7583A). Evidence for precession is detected in all four MYSOs
with precession-periods and angles ranging from $66-15480 \, {\rm yr}$ and
$6-36 ^\circ$ respectively. Should precession be the result of the influence
from a binary companion, we infer orbital radii of $30-1800\, {\rm au} $.
