TITLE:   GCN CIRCULAR
NUMBER:  35387
SUBJECT: GRB 231216A: Swift-BAT refined analysis
DATE:    23/12/17 05:01:41 GMT
FROM:    Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. Moss (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
T. Sbarrato (INAF-OAB), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 231216A (trigger #1202749)
(Sbarrato, et al., GCN Circ. 35378).  The BAT ground-calculated position is
RA, Dec = 39.778, 33.614 deg which is
   RA(J2000)  =  02h 39m 06.6s
   Dec(J2000) = +33d 36' 48.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.

The mask-weighted light curve shows a structure of multiple pulses.
The emission starts from T-5 s, peaks at T0 and ends at T+60 s.
T90 (15-350 keV) is 51.2 +- 3.1 sec (estimated error including systematics).

The time-averaged spectrum from T-1.12 to T+51.39 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.63 +- 0.20.  The fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.51 sec in the 15-150 keV band
is 1.8 +- 0.3 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/1202749/BA/