GCN Circular 9980
Subject
GRB 090929A, Swift-BAT refined analysis
Date
2009-09-30T21:06:52Z (15 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC),
S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL),
N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD),
K. Page (U Leicester),
D. M. Palmer (LANL),
A. M. Parsons (GSFC),
T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC),
T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
We report further analysis of Fermi-GBM GRB 090929A (Rau, et al.,
GCN Circ. 9962). The BAT ground-calculated position is the same
as stated in Cummings et al. (GCN Circ. 9966),
RA, Dec = 56.494, -5.952 or
RA (J2000) 03h 45m 57.9s
Dec (J2000) -05d 57' 50"
with an estimated 90% containment error radius of 3 arcmin. The
partial coding was 73-90% during the burst.
The mask-weighted lightcurve shows multiple peaks and spikes, at
T+1, T+2, T+4, T+5, and T+10 sec, where T0 is 04:33:07. T90 was
7 +- 2 seconds.
The time-averaged spectrum from T0 to T+12 sec is best fit by a
simple power-law model. The power law index of the time-averaged
spectrum is 0.96 +- 0.04. The fluence in the 15-150 keV band is
1.69 +- 0.07 x 10^-06 ergs/cm2. The 1-sec peak photon flux
measured from T+0.5 sec in the 15-150 keV band is
5.9 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90%
confidence level.