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GCN Circular 8808

Subject

GRB 090113: Swift-BAT refined analysis

Date

2009-01-14T00:07:29Z (16 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

GRB 090113: Swift-BAT refined analysis
 
J. Tueller (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
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), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-120 to T+302 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090113 (trigger #339852)
(Krimm, et al., GCN Circ. 8804Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 32.067, 33.436 deg, which is 
   RA(J2000)  =  02h 08m 16.0s 
   Dec(J2000) = +33d 26' 08.4" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
 
The mask-weighted light curve shows multiple peaks starting at ~T-10 sec
and ending at ~T+30 sec.  T90 (15-350 keV) is 9.1 +- 0.9 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.9 to T+10.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.10.  The fluence in the 15-150 keV band is 7.6 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.46 sec in the 15-150 keV band
is 2.5 +- 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/339852/BA/