[vsnet-grb-info 4288] GRB 070208, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6081
SUBJECT: GRB 070208, Swift-BAT refined analysis
DATE:    07/02/08 17:03:48 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:
 
Using the data set from T-239 to T+552 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 070208 (trigger #259714)
(Sato, et al., GCN Circ. 6074).  The BAT ground-calculated position is
RA, Dec = 197.896, 61.946 deg which is 
   RA(J2000)  = 13h 11m 35.0s 
   Dec(J2000) = 61d 56' 44.3" 
with an uncertainty of 3.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
 
The mask-weighted lightcurve shows two peaks. The first (at T_zero) is 
FRED-like with a duration of ~7 sec.  The second starts at ~T+35 sec
and ends at ~T+50 sec.  T90 (15-350 keV) is 48 +- 2 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-1.0 to T+47.8 is best fit by a
simple power-law model.  The power law index of the time-averaged
spectrum is 1.96 +- 0.37.  The fluence in the 15-150 keV band
is 4.3 +- 1.0 x 10^-07 erg/cm2.  The 1-sec peak photon flux measured
from T-0.26 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level. 

Fitting the two peaks separately with a simple power law model,
-2 to  5 s:   photon index = 2.17 -0.44 +0.53
25 to 50 s:   photon index = 1.69 -0.34 +0.36
Given the widths of the two peaks and that the second peak is 
spectrally harder than the first, we conclude that this burst
is a long GRB and is not a short hard burst with extended emission.