We investigated the long-term spin properties of the anomalous X-ray pulsar ( AXP ) 1E 1841-045 by performing a temporal analysis of archival RXTE observations spanning about 5.2 yr from 2006 September to 2011 December .
We identified two peculiar timing anomalies within \sim 1 yr of each other : a glitch with \Delta { \nu } / \nu \sim 4.8 \times 10 ^ { -6 } near MJD 54303 ; and an anti-glitch with \Delta { \nu } / \nu \sim - 5.8 \times 10 ^ { -7 } near MJD 54656 .
The glitch that we identified , which is the fourth glitch seen in this source in the 13 yr of RXTE monitoring , is similar to the last two detected glitches .
The anti-glitch from 1E 1841-045 , however , is the first to be identified .
The amplitude of the anti-glitch was comparable with that recently observed in AXP 1E 2259+586 .
We found no significant variations in the pulsed X-ray output of the source during either the glitch or the anti-glitch .
We discuss our results in relation to the standard pulsar glitch mechanisms for the glitch , and to plausible magnetospheric scenarios for the anti-glitch .