[vsnet-grb-info 20013] GRB 171103A: Swift-BAT refined analysis of a short GRB

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22099
SUBJECT: GRB 171103A: Swift-BAT refined analysis of a short GRB
DATE:    17/11/04 21:58:58 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
J. P. Norris (BSU), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171103A (trigger #785850)
(Ukwatta et al., GCN Circ. 22095).  The BAT ground-calculated position is
RA, Dec = 249.510, -10.206 deg which is
  RA(J2000)  =  16h 38m 02.4s
  Dec(J2000) = -10d 12' 22.9"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 65%.

The mask-weighted light curve shows a complex multi-peak structure.  It begins
with three peaks from -0.8 sec to +0.3 sec. This is followed by low-level, slowly
decaying emission out to ~T+20 sec and then a weaker peak at ~T+60 sec. The
spacecraft slewed away from the burst location at ~T+600 sec due to a
pre-planned slew. T90 (15-350 keV) is 3.90 +- 1.11 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.37 to T+4.67 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.31 +- 0.18.  The fluence in the 15-150 keV band is 3.8 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.37 sec in the 15-150 keV band
is 3.6 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The duration and hardness of this burst show it to be intermediate between the
short and long burst populations. Using a 8-ms binned light curve, the lag analysis
finds a lag of -0.5 +/- 4 ms for the 100-350 keV to 25-50 keV band, and -0.7 +/- 5 ms
for the 50-100 keV to 15-25 keV band. These values are consistent with those of
a short GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/785850/BA/