  We report the detection of large flux changes in the persistent X-ray flux of
SGR 1900+14 during its burst active episode in 1998. Most notably, we find a
factor ~700 increase in the non-burst X-ray flux following the August 27th
flare, which decayed in time as a power-law. Our measurements indicate that the
pulse fraction remains constant throughout this decay. This suggests a global
flux enhancement as a consequence of the August 27th flare rather than
localized heating. While the persistent flux has since recovered to the
pre-outburst level, the pulse profile has not. The pulse shape changed to a
near sinusoidal profile within the tail of the August 27th flare (in
gamma-rays) and this effect has persisted for more than 1.5 years (in X-rays).
The results presented here suggest the magnetic field of the neutron star in
SGR 1900+14 was significantly altered (perhaps globally) during the giant flare
of August 27.
