[vsnet-grb-info 2798] GRB 060202: Refined analysis of the Swift-BAT burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4635
SUBJECT: GRB 060202:  Refined analysis of the Swift-BAT burst
DATE:    06/02/02 17:29:35 GMT
FROM:    Craig Markwardt at NASA/GSFC/UMD  <craigm at milkyway.gsfc.nasa.gov>

D. Hullinger (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hinshaw (GSFC-SPSYS), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), 
K. McLean (LANL), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the data set from T-300 to T+303 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060202 (trigger #179968)  
(Fox, et al., GCN 4629).  The BAT ground-calculated position
is (RA,Dec) = 35.822, 38.381  deg {2h 23m 17.3s, 38d 22' 53.3"} (J2000)
+- 2.0 arcmin, (radius, sys+stat, 90% containment).  The partial coding 
was 61%.

The mask-tagged light curve shows two broad main peaks with roughly
equal peak count rates.  The first peak is from approximately T-40 to
T+40 sec and the second roughly from T+ ~70 to T+210 sec. The second
peak appears to be spectrally softer than the first peak.  We note
that XRT observations (Morris, et al, GCN 4632) started at T+148.8
seconds and thus overlapped with ~70 seconds of the prompt emission
detected by BAT.  T90 (15-350 keV) is (203.7 +- 20) sec (estimated
error including systematics).
 
The time-averaged spectrum from T-36.1 to T+196.6 is best fit by 
a simple power-law model.   The power law index of the time-averaged 
spectrum is 1.78 +- 0.13. The fluence in the 15-150 keV band 
is (2.4 +- 0.2) x 10^-06 erg/cm2.  The 1-sec peak photon flux measured from 
T-6.46 sec in the 15-150 keV band is (0.5 +- 0.2) ph/cm2/sec.  
All the quoted errors are at the 90% confidence level.