[vsnet-grb-info 5855] GRB 080320, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7505
SUBJECT: GRB 080320, Swift-BAT refined analysis
DATE:    08/03/22 14:06:04 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

K. McLean (GSFC/UMD), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Grupe (PSU),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-119 to T+183 sec from the telemetry downlinks,
we report further analysis of BAT GRB 080320 (trigger #306858)
(Grupe, et al., GCN Circ. 7473).  The BAT ground-calculated position is
RA, Dec = 177.763, 57.162 deg, which is 
   RA(J2000)  =  11h 51m 03.1s 
   Dec(J2000) = +57d 09' 42.6" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 93%.
 
The mask-weighted light curve shows a FRED peak starting at ~T-5 sec,
peaking at ~T+0, and ending at ~T+35 sec.  There a possible (3 sigma)
precursor peak at ~T-55 sec with a width of about 5 sec.
T90 (15-350 keV) is 14 +- 2 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.7 to T+13.8 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.70 +- 0.22.  The fluence in the 15-150 keV band is 2.7 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.15 sec in the 15-150 keV band
is 0.6 +- 0.1 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/306858/BA/