[vsnet-grb-info 17767] SGR 0755-2933, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19207
SUBJECT: SGR 0755-2933, Swift-BAT refined analysis
DATE:    16/03/17 22:10:48 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

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

Using the data set from T-60 to T+303 sec from the recent telemetry
downlink,
we report further analysis of SGR 0755-2933 (trigger #679432)
(Barthelmy, et al., GCN Circ. 19204).  The BAT ground-calculated position is
RA, Dec = 118.863, -29.572 deg which is
  RA(J2000)  =  07h 55m 27.0s
  Dec(J2000) = -29d 34' 20.3"
with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.

The mask-weighted light curve shows a single short spike of duration ~ 30
ms.
There is significant emission only below 50 keV. T90 (15-25 keV)
is 0.024 +- 0.009 sec (estimated error including systematics).

The time-averaged spectrum from T-0.004 to T+0.024 sec is best fit by a
simple
power-law model.  The power law index of the time-averaged spectrum is
3.81 +- 0.74.  The fluence in the 15-150 keV band is 5.9 +- 1.8 x 10^-9
erg/cm2.
The 1-sec peak photon flux measured from T-0.49 sec in the 15-150 keV band
is 0.3 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

As of T+19 hours, BAT has detected no further bursts from this source, and
the
BAT on-board detection history shows no previous signs of activity over the
life
of the mission since 2005.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/679432/BA/