TITLE:   GCN CIRCULAR
NUMBER:  22253
SUBJECT: GRB 171212A/Swift J1935.7+2036: Swift-BAT refined analysis
DATE:    17/12/13 13:56:37 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

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

Using the data set from T-240 to T+1004 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 171212A (trigger #796778)
(Tohuvavohu et al., GCN Circ. 22243).  The BAT ground-calculated position is
RA, Dec = 293.920, 20.597 deg which is
  RA(J2000)  =  19h 35m 40.8s
  Dec(J2000) = +20d 35' 49.6"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-30 s and ends at ~T+100 s, with some weak emissions lasting till ~ T+370 s.
T90 (15-350 keV) is 320 +- 72 sec (estimated error including systematics).

The time-averaged spectrum from T-28.82 to T+371.18 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.23 +- 0.14.  The fluence in the 15-150 keV band is 3.4 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+90.68 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/796778/BA/