A. Copete, J. Grindlay (Harvard)
S. Barthelmy, C. Markwardt, N. Gehrels (NASA/GSFC)
We report the detection of a bright GRB by the BAT Slew Survey (BATSS)
in the slew that started at 08:59:02 and lasted 151 sec. The ground-
calculated position is RA, Dec = 225.910, +17.224 deg, which is
RA (J2000) = 15h 03m 38s
Dec(J2000) = +17d 13' 26"
with an uncertainty of 1.91 arcmin (90% confidence, including
systematics). The detection was triggered by simultaneous independent
detections of 86.0 sigma and 41.8 sigma from imaging in the 15-50 keV
and 50-150 keV energy bands, respectively. The burst mask-tagged
lightcurve lightcurve in the 15-150 keV band shows a strong and broad
multi-peaked emission structure starting at T+25sec as the burst
enters the BAT field-of-view, lasting 48 sec, and peaking 6 times at T
+29, T+35, T+38, T+47, T+58 and T+62sec. This is followed by a weaker
broad peak starting at T+87sec, lasting 28sec and peaking at T+100sec.
T90 = 65.0sec and T50 = 17.0sec.
The time-averaged spectrum over the 120 sec exposure time of the
source is best fit by a power law with an exponential cutoff, with
photon index 1.42 and high-energy cut at 319 keV. The fluence in the
15-150 keV band is 1.6 x 10^-5 erg/cm^2, and the peak 1-sec flux is
6.5 x 10^-7 erg/cm^2/sec at T+38sec. A follow-up Swift ToO observation
for this burst has been scheduled.