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GCN Circular 20912

Subject

GRB 170318A: Swift-BAT refined analysis

Date

2017-03-18T18:57:59Z (7 years ago)

From

Hans Krimm at NASA-GSFC/NSF <hans.krimm@nasa.gov>

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

Using the data set from T-239 to T+483 sec from the recent telemetry 
downlink,
we report further analysis of BAT GRB 170318A (trigger #743065)
(Sbarufatti, et al., GCN Circ. 20904Not found
 
 
). The BAT ground-calculated 
position is
RA, Dec = 305.662, 28.408 deg which is
    RA(J2000)  =  20h 22m 38.9s
    Dec(J2000) = +28d 24' 30.5"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 43%.

The mask-weighted light curve shows a single FRED-shaped pulse that starts
approximately T+20 sec, peaks at T+2 sec and decays to background by
T+100 sec.  T90 (15-350 keV) is 133.7 +- 42.8 sec (estimated error 
including systematics).

The time-averaged spectrum from -21.544 to 175.788 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.11.  The fluence in the 15-150 keV band is 3.7 +- 0.3 x 
10^-06erg/cm2.
The 1-sec peak photon flux measured from T+1.87 sec in the 15-150 keV band
is 1.2 +- 0.3 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/743065/BA/