TITLE:   GCN CIRCULAR
NUMBER:  23335
SUBJECT: GRB 181013A: Swift-BAT refined analysis
DATE:    18/10/13 18:36:22 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL)  (i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181013A (trigger #866783)
(D'Avanzo, et al., GCN Circ. 23332).  The BAT ground-calculated position is
RA, Dec = 207.661, 40.107 deg, which is 
   RA(J2000)  =  13h 50m 38.5s 
   Dec(J2000) = +40d 06' 26.8" 
with an uncertainty of 3.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 81%.
 
The mask-weighted light curve shows peaks starting at ~T-5 sec and ending
at ~T+120 sec.  T90 (15-350 keV) is 104.1 +- 53.5 sec (estimated error
including systematics).
 
The time-averaged spectrum from T+18.37 to T+123.97 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.82 +- 0.75.  The fluence in the 15-150 keV band is 3.0 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+18.80 sec in the 15-150 keV band
is 0.5 +- 0.2 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/866783/BA/