GCN Circular 5964
Subject
GRB 061222A, Swift-BAT refined analysis
Date
2006-12-22T06:36:47Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
GRB 061222A, Swift-BAT refined analysis
J. Tueller (GSFC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), T. Ukwatta (UMD)
on behalf of the Swift-BAT team:
Using the data set from T-240 to T+302 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 061222A (trigger #252588)
(Grupe, et al., GCN Circ. 5954). The BAT ground-calculated position
is RA, Dec = 358.258, 46.527 deg which is
RA(J2000) = 23h 53m 1.9s
Dec(J2000) = 46d 31' 37.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 70%.
The mask-weighted lightcurve shows the emision starting at T-100 sec
with a small peak at T_zero, and then a 10-sec FRED peak starting at T+25 sec.
It is followed by two 10-sec peaks at T+50 and T+65 sec; then a large peak
at T+88 sec with a FWHM of ~12 sec and the emission returns to background
at T+115 sec. T90 (15-350 keV) is 72 +- 3 sec (estimated error including
systematics). At this time, there is a gap in the downlinked data
from T-180 sec to T-110. A further Circular will be issued if there is
burst activity in this interval.
The time-averaged spectrum from T-2.5 to T+117.7 is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.39 +- 0.04. The fluence in the 15-150 keV band is 8.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+86.54 sec in the 15-150 keV band
is 9.2 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.