TITLE:   GCN CIRCULAR
NUMBER:  8390
SUBJECT: GRB 081017, Swift-BAT refined analysis
DATE:    08/10/18 13:56:26 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

J. Tueller (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
O. Godet (U Leicester), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD),
D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), T. N. Ukwatta (GWU)
(i.e. 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 GRB 081017 (trigger #331964)
(Godet, et al., GCN Circ. 8388).  The BAT ground-calculated position is
RA, Dec = 230.209, -32.790 deg which is 
   RA(J2000)  =  15h 20m 50.1s 
   Dec(J2000) = -32d 47' 23.3" 
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
 
The mask-weighted light curve shows a broad lo-level emission with some
structure starting at ~T-70 and ending around T+400 sec.  The spacecraft slewed
to the next pre-planned observing target at T+400 sec such that the partial coding
of this burst location decreased to a small value.  As such the statisitical
error on the flux measurement increased to the point that we can only say
there is a hint of emission out to around T+700 sec.
T90 (15-350 keV) is 320 +- 50 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.0 to T+320.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.64 +- 0.23.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band
is 0.07 +- 0.01 ph/cm2/sec.  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/331964/BA/