GCN Circular 5174
Subject
GRB 060526: Refined analysis of the Swift-BAT burst
Date
2006-05-27T17:51:50Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
C. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU),
G. Sato (GSFC/JSPS/USRA), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-119 to T+1000 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060526 (trigger #211957)
(Campana, et al., GCN 5162 & 5163). The BAT ground-calculated position
is RA,Dec = 232.838,+0.292 deg {15h 31m 21.0s,+0d 17' 32.9"} (J2000)
+- 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding
was 61%.
As noted in GCN 5163, there are two well separated episodes of emission
detected in the BAT instrument.
The initial emission contains two FRED-like peaks, the first starting at
T-3sec, peaking at T+1, and ending at T+5 sec; and the second starts
at T+6 sec, peaks at T+7 sec, and returns back to the background level
at T+13 sec. T90 (15-350 keV) for this first episode is 13.8 +- 2 sec
(estimated error including systematics). The scond episode consists
of a single symmetric peak at T+250 sec (230 to 270 sec). This second
episode is coicident with the XRT flare described in GCN 5168.
For the first episode, the time-averaged spectrum from T-1.3 to T+17.0
is best fit by a simple power-law model. The power law index
of the time-averaged spectrum is 1.66 +- 0.20. The fluence
in the 15-150 keV band is 4.9 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.17 sec in the
15-150 keV band is 1.7 +- 0.2 ph/cm2/sec.
For the second episode, the time-averaged spectrum from T+230 to T+270
is best fit by a simple power-law model. The power law index
of the time-averaged spectrum is 2.07 +- 0.18. The fluence
in the 15-150 keV band is 5.9 +- 0.6 x 10^-7 erg/cm2. This is slightly
more fluence than the first episode, but only about half the peak flux.
All the quoted errors are at the 90% confidence level.