TITLE:   GCN CIRCULAR
NUMBER:  43354
SUBJECT: GRB 260101A: Swift-BAT refined analysis
DATE:    26/01/09 03:00:04 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), 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-239 to T+1066 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 260101A (trigger #1429608)
(Cenko, et al., GCN Circ. 43285).  The BAT ground-calculated position is
RA, Dec = 86.442, 63.583 deg which is
   RA(J2000)  =  05h 45m 46.2s
   Dec(J2000) = +63d 34' 57.2"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows a complex light curve with many emission episodes. T90 (15-350 keV) is 48.00 +- 16.00 sec (estimated error including systematics).

The time-averaged spectrum from T-31.26 to T+64.74 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.28 +- 0.23,
and Epeak of 109.2 +- 64.4 keV (chi squared 55.17 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 4.5 +- 0.2 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+24.24 sec in the 15-150 keV band is
4.6 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.62 +- 0.06 (chi squared 62.07 for 57 d.o.f.).  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/1429608