[AAVSO-HEN] GRB 060111: Swift-BAT Refined Analysis

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4486
SUBJECT: GRB 060111: Swift-BAT Refined Analysis
DATE:    06/01/11 20:16:06 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <jayc at milkyway.gsfc.nasa.gov>

G. Sato (ISAS), L. Barbier (GSFC), S. Barthelmy (GSFC), 
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC), 
D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
F. Marshall (GSFC), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), A. Smale (NASA HQ), J. Tueller (GSFC), 
on behalf of the Swift-BAT team:

Using the data set from T-299 to T+303.0 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060111 (trigger #176818)  
(Zane, et al., GCN 4479).  The BAT ground-calculated position is 
(RA,Dec) = 276.195, 37.596 {18h 24m 47.3s, 37d 35' 44.1"} (deg; J2000)
+- 0.8 arcmin, (radius, sys+stat, 90% containment).  The partial coding 
was 98%.

The light curve is a single peak, rise slightly faster than its decay.
T90 (15-350 keV) is (13 +- 1) sec (estimated error including 
systematics).  There is a small bump of marginal significance in the 
15-50 keV band at T+280, the time of the x-ray flare observed by the
XRT (GCN circ. #4481, Goad et al.).
 
The time-averaged spectrum from T-0.7 to T+14.7 is best fit by a
cut-off power law with an Epeak of (72 +14, -8) keV and a photon
index of 0.8 +- 0.3.  The fluence in the 15-150 keV band is (1.18 +-
0.05) x 10^-06 erg/cm2.  A simple power law also gives an acceptable
fit, with a photon index of 1.63 +/- 0.07 and a fluence of (1.25 +-
0.05) x 10^-06 erg/cm2.  The 1-sec peak photon flux measured from
T+4.3 sec in the 15-150 keV band is (1.72 +- 0.15) ph/cm2/sec.  All
the quoted errors are at the 90% confidence level.