TITLE:   GCN CIRCULAR
NUMBER:  45930
SUBJECT: GRB 261011A: Swift-BAT refined analysis
DATE:    26/10/13 00:39:46 GMT
FROM:    Amy <yarleen@gmail.com>

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) (i.e. the Swift-BAT team):

Using the data set from T-179 to T+723 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 261011A (trigger #1516664)
(Cenko et al., GCN Circ. 45896).  The BAT ground-calculated position is
RA, Dec = 21.911, -21.550 deg which is
   RA(J2000)  =  01h 27m 38.7s
   Dec(J2000) = -21d 33' 00.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 29%.

The mask-weighted light curve shows a multi-peaked structure that starts
~T+100 s and ends at ~T+210 s. T90 (15-350 keV) is 78.90 +- 18.49 sec
(estimated error including systematics). Note that the particularly unusual
light curve mentioned in the original circular (Cenko et al., GCN Circ.
45896) is no longer visible in the ground analysis. Further investigation
shows that there were some noisy detectors producing coincidental
pulse-like structures around the GRB time, and thus those pulses seen in
the raw light curve prior to ~T+100 s are not astrophysical.

The time-averaged spectrum from T+103.61 to T+208.74 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.50 +- 0.07.  The fluence in the 15-150 keV band is 6.3 +- 0.3 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+171.74 sec in the
15-150 keV band is 3.0 +- 0.4 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/1516664