[vsnet-grb-info 20840] GRB 180709A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22938
SUBJECT: GRB 180709A: Swift-BAT refined analysis
DATE:    18/07/09 20:48:13 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

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

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180709A (trigger #846868)
(Marshall et al., GCN Circ. 22930).  The BAT ground-calculated position is
RA, Dec = 38.086, 60.333 deg which is
  RA(J2000)  =  02h 32m 20.7s
  Dec(J2000) = +60d 19' 59.4"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 81%.

The mask-weighted light curve shows a single-peaked structure that starts
at ~T0 and peaks at ~T+10 s. The main structure ends at ~T+40 s, with some
tail emission lasting till ~T+240 s. T90 (15-350 keV) is 215.1 +- 28.9 sec
(estimated error including systematics).

The time-averaged spectrum from T+0.54 to T+243.46 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.37 +- 0.23.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+8.73 sec in the 15-150 keV band
is 0.6 +- 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/846868/BA/