G. Sato (ISAS), L. Angelini (GSFC-JHU), L. Barbier (GSFC),
S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
N. Gehrels (GSFC), J. Grenier (MPE), D. Hullinger (UMD),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), T. Mitani (ISAS),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC),
on behalf of the Swift/BAT team:
At 06:45:09.76 UT Swift-BAT detected GRB 050813 (trigger=150139) (GCN
Circ 3788, Retter et al.). The refined BAT ground position is
(RA,Dec) = 241.988, +11.246, [deg; J2000] +- 3 arcmin, (95%
containment radius). The partial coding was 57%. This is 7 arcsec from the
XRT position (Morris et al., GCN 3790).
The burst has a short spike lasting ~32 msec, overlayed on broader
peak of duration ~0.6 sec. There is a hint of a second peak at T+1.3
seconds. T90 (15-350 keV) is (0.6 +- .1) seconds (estimated error
The photon index of the time-averaged spectrum is 1.19 +- 0.33.
The fluence in the 15-350 keV band is (1.24 +- 0.46) x 10^-7 erg/cm2.
The 1-s peak photon flux measured from T+0.1 second in the 15-350
band is (1.22 +- 0.26) ph/cm2/s. All the quoted errors are at the 90%