TITLE:   GCN CIRCULAR
NUMBER:  26132
SUBJECT: GRB 191031C: Swift-BAT refined analysis
DATE:    19/11/01 19:06:54 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

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

Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 191031C (trigger #932595)
(Ambrosi, et al., GCN Circ. 26108).  The BAT ground-calculated position is
RA, Dec = 115.880, -62.322 deg which is 
  RA(J2000)  =  07h 43m 31.2s 
  Dec(J2000) = -62d 19' 20.1" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 24%.

The mask-weighted light curve shows several peaks.  The first begins around 
T-40 sec and runs until T-20 sec.  The second, brightest, peak begins immediately
after, peaks around T+5 sec, and decays to background by T+120 sec. There are
several weak peaks superimposed on this one, the largest coming around T+45 sec.  
T90 (15-350 keV) is 93.2 +- 19.0 sec (estimated error including systematics).

The time-averaged spectrum from T-37.98 to T+112.66 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.07.  The fluence in the 15-150 keV band is 7.2 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+4.04 sec in the 15-150 keV band
is 4.6 +- 0.5 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/932595/BA/