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GCN Circular 9337

GRB 090510: Swift-BAT refined analysis
2009-05-10T06:08:40Z (15 years ago)
Scott Barthelmy at NASA/GSFC <>
T. N. Ukwatta (GWU) S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
E. A. Hoversten (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD),
D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 090510 (trigger #351588)
(Hoversten, et al., GCN Circ. 9331).  The BAT ground-calculated position is
RA, Dec = 333.552, -26.598 deg, which is 
   RA(J2000)  =  22h 14m 12.6s 
   Dec(J2000) = -26d 35' 51.1" 
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 16%.
The mask-weighted light curve shows a small precursor peak at ~T-0.54 sec
(width ~ 30 msec).  Then the main peak starts at ~T-0.05 sec, peaks at T+0.04 sec
with a width of ~50 msec.  Then come two smaller peaks at T+0.24 and T+0.32 sec,
each about 40 msec in width.  At the 3-sigma level, there is the possibility
of low-level emission between T+110 sec to ~T+170 sec.  T90 (15-350 keV)
is 0.3 +- 0.1 sec (estimated error including systematics).
The time-averaged spectrum from T+0.0 to T+0.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.98 +- 0.20.  The fluence in the 15-150 keV band is 3.4 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band
is 9.7 +- 1.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
The results of the batgrbproduct analysis are available at
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