15 Years Going Steady – Timing the Magnetar 1E 1841-045

We report on a long-term monitoring campaign of 1E 1841−045, the 12-s anomalous X-ray pulsar and magnetar candidate at the center of the supernova remnant Kes73. We have obtained approximately monthly observations of the pulsar with the Rossi X-ray Timing Explorer (RXTE) spanning over two years, during which time 1E 1841−045 is found to be rotating with sufficient stability to derive a phase-connected timing solution. A linear ephemeris is consistent with observations of the pulse period made over the last 15 yrs with the Ginga, ASCA, RXTE, & BeppoSAX observatories. Phase residuals suggest the presence of “timing noise”, as is typically observed from young radio pulsars. These results confirm a rapid, constant spin-down for the pulsar, which continues to maintain a steady flux; this is inconsistent with most accretion scenarios.