TITLE:   GCN CIRCULAR
NUMBER:  26286
SUBJECT: GRB 191123A: Swift-BAT refined analysis
DATE:    19/11/23 22:52:53 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 191123A (trigger #939079)
(Tohuvavohu, et al., GCN Circ. 26279).  The BAT ground-calculated position is
RA, Dec = 215.289, 22.823 deg which is 
  RA(J2000)  =  14h 21m 09.3s 
  Dec(J2000) = +22d 49' 23.5" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.

The mask-weighted light curve shows a pair of pulses, each with some sub-
structure.  The first starts at ~T-10 sec, peaks at T+0 and decays by T+40 sec.
The second pulse starts at T+110 sec, peaks soon afterward and decays by 
T+180 sec.  T90 (15-350 keV) is 275.1 +- 102.4 sec (estimated error including 
systematics).

The time-averaged spectrum from -2.1 to 288.1 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.67 +- 0.25.  The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+111.77 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/939079/BA/