[vsnet-grb-info 19070] GRB 170205A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20613
SUBJECT: GRB 170205A: Swift-BAT refined analysis
DATE:    17/02/06 14:52:41 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm at nsf.gov>

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

Using the data set from T-10 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170205A (trigger #736843)
(Troja, et al., GCN Circ. 20603).  The BAT ground-calculated position is
RA, Dec = 262.157, -0.058 deg which is
  RA(J2000)  =  17h 28m 37.8s
  Dec(J2000) = -00d 03' 30.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 91%.

The mask-weighted light curve shows that the burst consisted of two peaks of
roughly equal peak counts, the first from T-2 sec to T+12 sec and the second
from T+12 sec to T+30 sec.  T90 (15-350 keV) is 26.1 +- 3.2 sec (estimated
error including systematics). It is possible that the burst is longer than this since
there was no data before T-10 seconds, following the re-enabling of data collection
after an SAA passage.

The time-averaged spectrum from T-1.42 to T+46.40 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.85 +- 0.06.  The fluence in the 15-150 keV band is 3.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band
is 4.3 +- 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/736843/BA/