[vsnet-grb-info 23856] GRB 191004B: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25955
SUBJECT: GRB 191004B: Swift-BAT refined analysis
DATE:    19/10/05 04:07:48 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at milkyway.gsfc.nasa.gov>

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

Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 191004B (trigger #927839)
(Cenko, et al., GCN Circ. 25947).  The BAT ground-calculated position is
RA, Dec = 49.200, -39.637 deg, which is
   RA(J2000)  =  03h 16m 47.9s
   Dec(J2000) = -39d 38' 15.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.

The mask-weighted light curve shows multiple overlapping peaks starting at
T-1 sec, peaking at ~T+7 sec, and ending at ~T+45 sec.
T90 (15-350 keV) is 37.7 +- 14.9 sec (estimated error including systematics).

The time-averaged spectrum from T-1.45 to T+56.17 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.10 +- 0.08.  The fluence in the 15-150 keV band is 2.5 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.75 sec in the 15-150 keV band
is 5.0 +- 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/927839/BA/