GCN Circular 45985

S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha
(GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss
(GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T.
Sakamoto (AGU), M. H. Siegel (PSU) (i.e. the Swift-BAT team):

Using the data set from T-179 to T+717 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 261017A (trigger #1519536)
(Siegel et al., GCN Circ. 45974
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 ).  The BAT ground-calculated position is
RA, Dec = 139.901, 12.644 deg which is
   RA(J2000)  =  09h 19m 36.2s
   Dec(J2000) = +12d 38' 40.0"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 92%.

The mask-weighted light curve shows a main structure with multiple
overlapping pulses that starts and peaks at ~T0, and ends at ~T+10 s. In
addition, there are some weaker pulses that starts from ~T+50 s and ends at
~T+100 s. T90 (15-350 keV) is 89.36 +- 4.78 sec (estimated error including
systematics).

The time-averaged spectrum from T-0.70 to T+93.11 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.09 +- 0.16.  The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T-0.22 sec in the 15-150
keV band is 1.3 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.

The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1519536