[vsnet-grb-info 19195] GRB 170311A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20855
SUBJECT: GRB 170311A: Swift-BAT refined analysis
DATE:    17/03/12 16:08:13 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
(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 170311A (trigger #741965)
(Cummings, et al. GCN Circ. 20846).  The BAT ground-calculated position is
RA, Dec = 280.539, -30.041 deg which is
  RA(J2000)  =  18h 42m 09.4s
  Dec(J2000) = -30d 02' 27.1"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.

The mask-weighted light curve shows a complex structure with several
overlapping peaks that starts at ~T-1 s and ends at ~T+6 s. T90 (15-350 keV)
is 6.32 +- 0.96 sec (estimated error including systematics).

The time-averaged spectrum from T-0.92 to T+6.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.38 +- 0.32.  The fluence in the 15-150 keV band is 2.5 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.73 sec in the 15-150 keV band
is 0.8 +- 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/741965/BA/