TITLE:   GCN CIRCULAR
NUMBER:  20456
SUBJECT: GRB 170113A: Swift-BAT refined analysis
DATE:    17/01/14 03:03:42 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
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-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170113A (trigger #732526)
(Evans et al., GCN Circ. 20446).  The BAT ground-calculated position is
RA, Dec = 61.735, -71.933 deg which is
   RA(J2000)  =  04h 06m 56.5s
   Dec(J2000) = -71d 55' 58.0"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T0 and ends at ~T+25 s. The main peak occurs at ~T+2 s. T90 (15-350 keV)
is 20.66 +- 4.44 sec (estimated error including systematics).

The time-averaged spectrum from T-0.61 to T+23.84 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.75 +- 0.59,
and Epeak of 73.3 +- 33.6 keV (chi squared 72.24 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.7 +- 0.7 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+1.63 sec in the 15-150 keV band is
1.1 +- 0.1 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.57 +- 0.13 (chi squared 79.06 for 57 d.o.f.).  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/732526/BA/