TITLE:   GCN CIRCULAR
NUMBER:  20829
SUBJECT: GRB 170306A, Swift-BAT refined analysis
DATE:    17/03/07 02:59:37 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), N. Gehrels (GSFC),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
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 170306A (trigger #741220)
(Markwardt et al., GCN Circ. 20819).  The BAT ground-calculated position is
RA, Dec = 263.087, -44.765 deg which is
   RA(J2000)  =  17h 32m 20.9s
   Dec(J2000) = -44d 45' 52.5"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 29%.

The mask-weighted light curve shows a pulse that starts at ~T-7 s and ends
at ~T+20 s. In addition, there is a hint of some weak emissions from ~T-100 s
to ~T-80 s. T90 (15-350 keV) is 17.8 +- 6.7 sec (estimated error including systematics).

The time-averaged spectrum from T-7.1 to T+19.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.98 +- 0.28.  The fluence in the 15-150 keV band is 8.3 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+10.93 sec in the 15-150 keV band
is 1.3 +- 0.4 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/741220/BA/