Mode changing in J1909 ? 3744: the most precisely timed pulsar

ABSTRACT We present baseband radio observations of the millisecond pulsar J1909 ? 3744, most precisely timed pulsar, using MeerKAT telescope as part MeerTime timing array campaign. During a particularly bright scintillation event showed strong evidence pulse mode changing, among first pulsars and shortest duty cycle to do so. Two modes appear be present, with weak (lower signal-to-noise ratio) arriving 9.26 ± 3.94 ?s earlier than counterpart. Further, we new value jitter noise for this 8.20 0.14 ns in one hour, finding it consistent previous measurements taken (9 3 ns) Parkes (8.6 0.8 telescopes, but inconsistent previously precise measurement Green Bank (14 0.5 ns). Timing analysis on individual is carried out find an approximate $10\, \mathrm{per\,cent}$ improvement precision achievable through only opposed full sample pulses. By forming model average from templates two modes, time them simultaneously demonstrate that can also achieved regular observations. discuss impact degree would have searches stochastic gravitational wave background, well similar all PTA pulsars.