GCN Circular 5578
Subject
GRB 060919, Swift-BAT refined analysis
Date
2006-09-19T14:55:29Z (18 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
G. Sato (GSFC/ISAS), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
C. Guidorzi (Univ Bicocca&INAF-OAB), D. Hullinger (BYU-Idaho),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+950 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060919 (trigger #230115)
(Guidorzi, et al., GCN Circ. 5575). The BAT ground-calculated position
is RA,Dec = 276.900, -50.994 deg {18h 27m 36.0s, -50d 59' 39.8"} (J2000)
+- 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 29%.
There is an initial FRED peak starting at T-1 sec, peaking at T+0,
and lasting out to T+5 sec. There is smaller, 4-sec wide FRED-like peak
starting at T+6 sec. There is an even smaller, 4-sec wide peak centered
at T+24 sec. We note that our initial circular using the raw TDRSS rate
lightcurves described a second episode of emission at T+300 sec.
Now using the masked-tagged light curves, this second episode was due
to a noisy detector in the instrument. T90 (15-350 keV) is 9.1 +- 0.2 sec
(estimated error including systematics).
The time-averaged spectrum from T-1.0 to T+9.0 is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.85 +- 0.19. The fluence in the 15-150 keV band
is 5.5 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured
from T-0.49 sec in the 15-150 keV band is 2.2 +- 0.3 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.