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[36.02] Large Changes in Source Flux and Spin-down Rate of SGR 1900+14

P. M. Woods, C. Kouveliotou, M. H. Finger (USRA/MSFC), E. Gogus (UAH), J. Swank (GSFC), D. A. Smith (U. Michigan)

We report on the detection of large flux changes in the persistent X-ray counterpart of SGR~1900+14 during its burst active episode in 1998. We find a power-law decay of the flux enhancement following the August 27^{\rm th} flare with the pulse fraction remaining constant. The constant pulse fraction suggests a global flux enhancement as a consequence of the August 27^{\rm th} flare rather than localized heating. The persistent flux has since recovered to the pre-outburst level, however, the pulse profile has not. The pulse shape changes observed within the tail of the August 27^{\rm th} flare (in \gamma-rays) have persisted for more than 1.5 years (in X-rays) and show no signs of recovery. We have also discovered a substantial increase in the average spin-down rate of SGR~1900+14, long after burst activity has ceased.