GRB 071006

J. R. Cummings (CRESST/NASA/GSFC) for the Swift-BAT team

At 06:41:40 UT on October 6, the Swift Burst Alert Telescope (BAT)
triggered on GRB 071006. The burst began just before a preplanned
slew, and no source was found automatically onboard. A source was 
found during later ground analysis, at a location of 
RA, Dec 335.282, -23.154, which is
   RA(J2000)  =  22h 21m 07s
   Dec(J2000) = -23d 09' 14"
with an uncertainty of 2 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows two small peaks
on top of a gradual rise to a large peak at T+32 sec. The total
duration is about 80 sec. The spectrum appears to be of average
hardness for a long GRB.

Because the burst was detected on the ground, there are no prompt
XRT data. We have requested a TOO to observe this burst on
October 10.

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
and T. Cline on behalf of the Konus-Wind team report:

The long GRB 071006 (Cummings, GCN 6858
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 ) triggered
Konus-Wind at T0=24133.617 s UT (06:42:13.617).

The burst started at T-T0 ~35 s and had a duration of ~60 s.
As observed by Konus-Wind the burst
had a fluence of 2.08(-1.25, +0.11)x10^-5 erg/cm2,
and a 256-ms peak flux measured from T0+1.264 s
of 2.66(-1.51, +0.45)x10^-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The spectrum integrated over the main peak (from T0 to T0+8.448 s)
is well fitted (in the 20 keV - 2 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep)
with alpha = 0.84(-0.26, +0.22)
and Ep = 334(-61, +95) keV (chi2 = 62.2/60 dof).
The fluence of this part is 8.52(-4.63, +0.47)x10^-6 erg/cm2.

All the quoted errors are at the 90% confidence level.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB071006_T24133/

C. B. Markwardt (GSFC/UMD), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), D. Palmer (LANL), P. Romano (Univ. Bicocca & INAF-OAB),
T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T0 to T+13 sec (which covers only one of the
minor peaks in the burst), we report further analysis of
BAT GRB 071006 (trigger #293250) (Cummings, et al., GCN Circ. 6858
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 ).  
The best BAT position is RA, Dec = 335.294 -23.147 deg which is
   RA(J2000)  =  22h 21m 10.4s
   Dec(J2000) = -23d 08' 47"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 6%.
 
We do not have a mask-weighted light curve for this event. The raw
light curve based on the whole detector rate shows 3 peaks of 
increasing amplitude, the two minor peaks at T-2 and T+10 sec, and the 
main peak at T+32 sec. The two smaller peaks are each about 6 seconds 
long and the larger about 30 seconds long. All the peaks are roughly 
symmetric. T90 is 50 +- 10 seconds (estimated error including 
systematics).
 
The time-averaged spectrum from T+0 to T+13 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.75 +- 0.21.  The fluence in the 15-150 keV band is
1.4 +- 0.2 x 10^-7 erg/cm2. 

The 1-sec peak photon flux occurs where no event data is available.
By comparing the portions of the raw light curve and the mask-weighted
light curve that do overlap, we extrapolate a peak flux of 
13 +- 3 ph/cm2/sec in the 15-150 keV band.  Similarly, we extrapolate a 
total fluence of  1.0 +- 0.3 x 10^-6 erg/cm2.  All the quoted errors
are at the 90% confidence level.