[vsnet-grb-info 14715] GRB 140323A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16029
SUBJECT: GRB 140323A: Swift-BAT refined analysis
DATE:    14/03/23 19:27:36 GMT
FROM:    Hans Krimm at NASA-GSFC  <hans.a.krimm at nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), J. Tueller (GSFC),
T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+693 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140323A (trigger #592916)
(Troja, et al., GCN Circ. 16027).  The BAT ground-calculated position is
RA, Dec = 356.975, -79.916 deg which is
    RA(J2000)  =  23h 47m 54.1s
    Dec(J2000) = -79d 54' 57.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 12%.

The mask-weighted light curve shows a complex structure.  Low-level emission
starts around T-60 sec, then the first episode runs from T-20 to T+55 sec, and
is a slow rise and fall with multiple sub-peaks superimposed.  The second
episode has a similar shape and runs from T+60 to T+110 sec, followed by
more low-level emission out to T+140 sec.  The second episode is spectrally
softer than the first. T90 (15-350 keV) is 104.9 +- 2.6 sec (estimated error
including systematics).

The time-averaged spectrum from T-7.09 to T+117.37 sec is best fit by a
power law with an exponential cutoff.  This fit gives a photon index 1.35 +- 0.17,
and Epeak of 127.1 +- 59.2 keV (chi squared 50.15 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.6 +- 0.0 x 10^-05 erg/cm2
and the 1-sec peak flux measured from T+6.42 sec in the 15-150 keV band is
6.2 +- 0.7 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.64 +- 0.04 (chi squared 59.02 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/592916/BA/