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ATEL # 1041; R. Dib, V. M. Kaspi (McGill U), F. P. Gavriil (NASA/GSFC), P. M. Woods (Dynetics).
on 3 Apr 2007; 1:28 UT
Password Certification: Rim Dib (email@example.com)
Subjects: X-ray, Pulsars
We report the detection of a sudden spin-up and pulsed flux increase in the 6.5-s anomalous X-ray pulsar 1E 1048.1-5937 in regular timing observations made with RXTE. The event, which occured between MJD 54181 (2007 March 22) and 54187 (2007 March 28), but most likely on MJD 54186 (2007 March 27) can be characterized by a fractional increase in the rotational frequency of magnitude (deltaNU/NU = 2.7+/-0.7 x 10-6). Three post-glitch RXTE observations taken between March 28 and March 29 show that the pulsed flux increased by a factor of 2.5. These sudden changes follow a 2-year period of unusual stability of the source. Observations at other wavelengths are strongly encouraged.