A Second Glitch from the “Anomalous” X-Ray Pulsar 1RXS J170849.0–4000910

We report on 5.4 yr of phase-coherent timing, using the Rossi X-Ray Timing Explorer, of the X-ray pulsar 1RXS J170849.0-4000910 (1RXS J1708-4009), a member of the class known as "anomalous X-ray pulsars." This object exhibited a rotational glitch in 1999. Here we report a second, much larger rotational glitch that occurred ~1.5 yr after the first. We show that the recoveries from the two glitches are significantly different, with the first showing only a possible slow, approximately linear recovery, while the second showed a nearly complete recovery on a timescale of ~50 days. The approximately exponential recovery timescale of the second glitch is similar to that seen recently in 1E 2259+586 at the time of a major outburst. This suggests that 1RXS J1708-4009 undergoes similar bursting behavior, although with our sparse observations we have detected no other evidence of bursts from this source.