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GCN Circular 16699

Subject

GRB 140817A: Swift-BAT refined analysis

Date

2014-08-17T17:16:02Z (10 years ago)

From

Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>

J. R. Cummings, S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(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 140817A (trigger #609736)
(Sbarufatti, et al., GCN Circ. 16695Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 127.244, 58.191 deg which is
    RA(J2000)  =  08h 28m 58.5s
    Dec(J2000) = +58d 11' 27.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.
  
The mask-weighted light curve shows multiple sharp peaks from T-20 to T+12 seconds,
then a return to background levels until about T+170 seconds where 2 overlapping
FRED peaks begin, lasting until about T+250 seconds.  T90 (15-350 keV) is
244 +- 13 sec (estimated error including systematics).
  
The time-averaged spectrum from T-21.26 to T+270.27 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.48 +- 0.08.  The fluence in the 15-150 keV band is 4.6 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+2.64 sec in the 15-150 keV band
is 7.2 +- 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/609736/BA/