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XTE J1829-098 Predicted for Another Outburst in Early April

ATEL # 2007; C. B. Markwardt (U. Maryland & NASA/GSFC), J. Halpern (Columbia U.), J. H. Swank (NASA/GSFC)
on 4 Apr 2009; 22:45 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Craig B. Markwardt (

Subjects: Infra-Red, X-ray, Request for Observations, Binaries, Neutron Stars, Pulsars, Transients

XTE J1829-098 is a 7.8 second transient X-ray pulsar discovered by RXTE in 2004 (ATEL #317), having XMM, Chandra, and IR counterparts (Halpern & Gotthelf 2007, ApJ, 669, 579).

A long term light curve of XTE J1829-098 from regular RXTE PCA monitoring observations shows that its outbursts have a recurrence period of ~246 days and a duration of ~7 days. Based on our earlier prediction, RXTE caught an outburst of the source in August 2008, appearing to peak around 2008-08-04. If the recurrence period holds, the source is due to have another outburst soon, peaking within a few days of 2009-04-07.

Analysis of the pulsations observed during the August 2008 outburst reveal a period of 7.839783(6) s, and an apparent period derivative of about 6e-10 s/s. There is no additional obvious evidence for orbital modulation of the pulse arrival times. The fluxes at the peak of the August 2008 outburst in the 2-10, 10-20 and 20-40 keV bands were approximately 7.4, 6.9 and 2.2 respectively, in units of 1e-11 erg/cm^2/s.

If we interpret the 246 day outburst cycle as the orbital period, then XTE J1829-098 would have a quite long orbital period compared to other sources in the Pspin vs. Porb "Corbet" diagram with a similar spin period. The properties of XTE J1829-098 strongly suggest that it is a wind-fed X-ray binary, probably a Be star binary.

PCA Scan light curve of XTE J1829-098

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