GCN Circular 3273
Subject
GRB 050416: Swift-BAT refined analysis
Event
Date
2005-04-16T16:25:32Z (21 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS),
M. Suzuki (Saitama), M. Tashiro (Saitama U.), J. Tueller (GSFC),
on behalf of the Swift/BAT team:
At 11:04:44.5 UT Swift-BAT detected GRB 050416 (trigger=114753)
(GCN Circ 3264, Sakamoto et al.). The refined BAT ground position
is (RA,Dec) = 188.490, 21.053, [deg; J2000] +- 3 arcmin, (95%
containment). This is 0.7 arc minutes from the position determined
by the XRT (GCN Circ 3268, Kennea, et al.).
The BAT mask weighted light curve shows a single peak of about one
second duration followed by a small bump. Most of the emission is
in the 15-50 keV band. T90 (15-350 keV) is (2.4 +- 0.2) seconds
(estimated error including systematics).
The photon index of the spectrum is 2.9 +- 0.2. The fluences in
the 15-50 keV band and in the 15-350 keV band are
(2.8 +- 0.2) x 10^-7 erg/cm2 and (3.8 +- 0.4) x 10^-7 erg/cm2 respectively.
The peak photon fluxes in the 15-50 keV band and in the 15-350 band are
(4.4 + 0.8) ph/cm2/s and (4.8 +- 0.6) ph/cm2/s respectively. All the
quoted errors are in 90% confidence level.
The BAT team cautions that while there appears to be a deficit of
counts below 20 keV, this is likely due to systematic errors in the
response matrix being accentuated by the steep spectrum.