[vsnet-grb-info 7531] GRB 090404: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9089
SUBJECT: GRB 090404: Swift-BAT refined analysis
DATE:    09/04/04 23:48:55 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

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),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),
T. N. Ukwatta (GWU), H. Ziaeepour (UCL-MSSL)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090404 (trigger #348428)
(Ziaeepour, et al., GCN Circ. 9086).  The BAT ground-calculated position is
RA, Dec = 239.233, 35.518 deg, which is 
   RA(J2000)  =  15h 56m 55.8s 
   Dec(J2000) = +35d 31' 03.4" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 89%.
 
The mask-weighted light curve shows at least 7 overlapping peaks starting
at ~T-50 sec and ending at ~T+150 sec.  T90 (15-350 keV) is 84 +- 14 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-35.2 to T+94.6 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.32 +- 0.08.  The fluence in the 15-150 keV band is 3.0 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+17.32 sec in the 15-150 keV band
is 1.9 +- 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/348428/BA/