GCN Circular 5831
Subject
GRB 061121, Swift-BAT refined analysis
Date
2006-11-21T21:37:11Z (18 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
E. Fenimore (LANL), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. L. Page (U Leicester),
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-240 to T+421 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 061121 (trigger #239899)
(Page, et al., GCN Circ. 5823). The BAT ground-calculated position
is RA,Dec = 147.228, -13.188 deg {9h 48m 54.8s, -13d 11' 16.6"} (J2000)
+- 0.9 arcmin, (radius, sys+stat, 90% containment). The partial coding
was 100%.
The mask-weighted lightcurve starts with small smooth pulse at ~T-5 sec
and returning to instrumental background level at T+20 sec. The the second
and much brighter started at ~T+50 sec with a series of overlapping peaks
the last of which was the brightest. Then there was roughly exponential decay
out to ~T+200 sec. T90 (15-350 keV) is 81 +- 5 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.8 to T+121.8 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum
is 1.41 +- 0.03. The fluence in the 15-150 keV band is
1.37 +- 0.02 x 10^-5 erg/cm2. The 1-sec peak photon flux measured
from T+74.48 sec in the 15-150 keV band is 21.1 +- 0.5 ph/cm2/sec.
The isotropic equivalent energy using the reported redshift of 1.314
(GCN Circ. 5826; Bloom, Perley & Chen) is 7e52 erg in
the 35 keV - 347 keV band at the GRB rest frame.
All the quoted errors are at the 90% confidence level.