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GCN Circular 9716

Subject
GRB 090726, Swift-BAT refined analysis
Date
2009-07-27T15:57:17Z (15 years ago)
From
Tilan Ukwatta at GSFC/GWU <tilan.ukwatta@gmail.com>
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), K. L. 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):

Using the data set from T-240 to T+962 sec from the
recent telemetry downlink, we report further analysis
of BAT GRB 090726 (trigger #358422) (Page, et al.,
GCN Circ. 9706).  The BAT ground-calculated position is
RA, Dec = 248.681, 72.866 deg which is
   RA(J2000)  =  16h 34m 43.5s
   Dec(J2000) = +72d 51' 56.5"
with an uncertainty of 1.7 arcmin, (radius, sys+stat,
90% containment). The partial coding was 85%.

The mask-weighted light curve shows a weak single peak
starting at ~T-40 sec, peaking at ~T+5 aec,
and ending at ~T+70 sec. T90 (15-350 keV) is
67.0 +/- 15.2 sec (estimated error including systematics).

The time-averaged spectrum from T-34.7 to T+47.3 sec is
best fit by a simple power-law model.  The power law
index of the time-averaged spectrum is 2.25 +/- 0.19.
The fluence in the 15-150 keV band is
8.6 +/- 1.0 x 10^-07 erg/cm2. The 1-sec peak photon
flux measured from T+7.30 sec in the 15-150 keV band
is 0.7 +- 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/358422/BA/
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