[vsnet-grb-info 6922] Swift-BAT refined analysis of trigger 334129

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8512
SUBJECT: Swift-BAT refined analysis of trigger 334129
DATE:    08/11/10 13:39:49 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
S. Immler (CRESST/GSFC/UMD)
(on behalf of the Swift-BAT team):

Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT possible burst GRB 081109B (trigger #334129)
(Immler, et al., GCN Circ. 8502).  Given the extremely weak recorded flux,
the lack of an XRT detection (private communication), and the specrtal softness,
this trigger is very likely not due to a GRB.  However, we can not completely
rule out a GRB orgin.  If it were due to a GRB, then the following would apply:

The BAT ground-calculated position is RA, Dec = 350.132, -55.912 deg,
which is 
   RA(J2000)  =  23h 20m 31.8s 
   Dec(J2000) = -55d 54' 42.8" 
with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
 
The mask-weighted light curve shows a weak peak starting at ~T+15 sec
and ending at ~T+115 sec.
 
The time-averaged spectrum from T+0.0 to T+128.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.21 +- 0.56.  The fluence in the 15-150 keV band is 2.3 +- 0.9 x 10^-7 erg/cm2.
All the quoted errors are at the 90% confidence level. 
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/334129/BA/