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GCN Circular 17596

Subject

GRB 150317A: Swift-BAT refined analysis

Date

2015-03-17T20:52:03Z (9 years ago)

From

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

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

Using the data set from T-236 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150317A (trigger #635148)
(Siegel, et al., GCN Circ. 17592Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 138.995, 55.477 deg which is
    RA(J2000)  =  09h 15m 58.8s
    Dec(J2000) = +55d 28' 38.7"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 78%.

The mask-weighted light curve shows three separate peaks, each of duration ~5 
seconds, with maxima at T+0, T+12 and T+23 seconds. T90 (15-350 keV) is 23.29 +- 
0.85 sec (estimated error including systematics).

The time-averaged spectrum from T-0.44 to T+24.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.52 +- 0.16.  The fluence in the 15-150 keV band is 6.5 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.15 sec in the 15-150 keV band
is 1.2 +- 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/635148/BA/