Outburst of the X-ray transient SAX J1818.6-1703 detected by INTEGRAL in   September 2003
  During the observation of the Galactic-center field by the INTEGRAL observatory on September 9, 2003, the IBIS/ISGRI gamma-ray telescope detected a short (several-hours-long) intense (~380 mCrab at the peak) outburst of hard radiation from the X-ray transient SAX J1818.6-1703. Previously, this source was observed only once in 1998 during a similar short outburst. We present the results of our localization, spectral and timing analyses of the object and briefly discuss the possible causes of the outburst. The release time of the bulk of the energy in such an outburst is appreciably shorter than the accretion (viscous) time that characterizes the flow of matter through a standard accretion disk. 
S. A. Grebenev (1) and R. A. Sunyaev (1,2) (1 - Space Research   Institute, Moscow, 2 - Max-Planck-Institut fur Astrophysik,...