[vsnet-grb-info 5115] GRB 070923, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6821
SUBJECT: GRB 070923, Swift-BAT refined analysis
DATE:    07/09/24 10:33:31 GMT
FROM:    Hans Krimm at NASA-GSFC  <krimm at milkyway.gsfc.nasa.gov>

J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
M. C. Stroh (PSU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+230 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 070923 (trigger #292004)
(Stroh, et al., GCN Circ. 6818).  The BAT ground-calculated position is
RA, Dec = 184.623, -38.294 deg which is
    RA(J2000)  = 12h 18m 29.5s
    Dec(J2000) = -38d 17' 38"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.

The mask weighted light curve shows a single peak of duration ~50 msec.
T90 (15-350 keV) is 0.05 +- 0.01 sec (estimated error including systematics).

The time-averaged spectrum from T+0.16 to T+0.37 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.02 +- 0.29.  The fluence in the 15-150 keV band is 5.0 +- 0.9 x 
10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.40 sec in the 15-150 keV band
is 2.4 +- 0.4 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.