TITLE:   GCN CIRCULAR
NUMBER:  22280
SUBJECT: GRB 171222A: Swift-BAT refined analysis
DATE:    17/12/24 12:41:04 GMT
FROM:    Hans Krimm at NASA-GSFC/NSF  <hans.krimm@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
J. L. Racusin (NASA/GSFC),  T. Sakamoto (AGU), M. Stamatikos (OSU),
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 171222A (trigger #799669)
(Racusin, et al., GCN Circ. 22265).  The BAT ground-calculated position is
RA, Dec = 148.273, 35.624 deg which is
    RA(J2000)  =  09h 53m 05.4s
    Dec(J2000) = +35d 37' 24.9"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.

The mask-weighted light curve shows multiple overlapping peaks in three 
groupings.
The first runs from approximately T-10 sec to T+50 sec, the second from 
T+50 sec
to T+90 sec, and the third, weakest group from T+90 sec to T+200 sec.
T90 (15-350 keV) is 174.8 +- 22.7 sec (estimated error including 
systematics).

The time-averaged spectrum from T+8.00 to T+209.82 sec is best fit by a 
simple
power-law model.  The power law index of the time-averaged spectrum is
2.07 +- 0.17.  The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-6 
erg/cm2.
The 1-sec peak photon flux measured from T+61.34 sec in the 15-150 keV band
is 0.7 +- 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/799669/BA/