We present an updated timing solution for the young , energetic pulsar PSR B1509 - 58 based on 21.3 years of radio timing data and 7.6 years of X-ray timing data .
No glitches have occurred in this time span , in contrast to other well-studied young pulsars , which show frequent glitches .
We report a measurement of the third frequency derivative of { \stackrel { \bf ... } { \textstyle \nu } } = ( -1.28 \pm 0.21 ) \times 10 ^ { -31 } s ^ { -4 } .
This value is 1.65 standard deviations from , i.e .
consistent with , that predicted by the simple constant magnetic dipole model of pulsar spin-down .
We measured the braking index to be n = 2.839 \pm 0.003 and show that it varies by 1.5 % over 21.3 yr due to contamination from timing noise .
Results of a low-resolution power spectral analysis of the significant noise apparent in the data yield a spectral index of \alpha = -4.6 \pm 1.0 for the red noise component .