GCN Circular 9979
Subject
GRB 090929B, Swift-BAT refined analysis
Date
2009-09-30T21:04:27Z (15 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
H. A. Krimm (GSFC/USRA),
S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL),
N. Gehrels (GSFC),
C. B. Markwardt (GSFC/UMD),
C. Pagani (PSU),
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):
Using the data set from T-239 to T+691 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 090929 (trigger
#371050) (Pagani, et al., GCN Circ. 9963). The BAT ground-calculated
position is RA, Dec = 117.712, -0.645 deg which is
RA(J2000) = 07h 50m 50.9s
Dec(J2000) = -00d 38' 41.2"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 63%.
The mask-weighted lightcurve shows many peaks interspersed with
intervals with no detected flux, from T-10 to T+380 sec when the source
left the coded field of view due to a observing constraint. There may
have been small and/or low-energy peaks beyond this time. The largest
peak was at about T+30 to T+40 sec. T90 (15-350 keV) was 360 +- 20 sec
(estimated error including systematics).
The time-averaged spectrum from T-9.8 to T+371.0 sec is best fit by a
simple power-law model. The power law index of the time-averaged
spectrum is 1.85 +- 0.08. The fluence in the 15-150 keV band is
5.9 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from
T+30.67 sec in the 15-150 keV band is 3.3 +- 0.2 ph/cm2/sec. All the
quoted errors are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/371050/BA/