GCN Circular 18829

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), A. Melandri (INAF-OAB),
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 160104A (trigger #669319) (Melandri , et al., GCN
Circ. 18815
Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 76.808, 11.334 deg which is
   RA(J2000)  =  05h 07m 13.9s
   Dec(J2000) = +11d 20' 01.2"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90%
containment). The partial coding was 100%.

The mask-weighted light curve shows a two-peak episode
with main peak starting ~T-3 sec, peaking at ~T+1 sec,
and ending around T+10 sec, where second weak
peak starts. The second pulse ends around ~T+20 sec.
T90 (15-350 keV) is 16.2 +- 2.5 sec (estimated
error including systematics).

The time-averaged spectrum from T-1.31 to T+17.65 sec is best
fit by a simple power-law model.  The power law index of the
time-averaged spectrum is 1.76 +- 0.19.  The fluence in the
15-150 keV band is 4.0 +- 0.5 x 10^-07 erg/cm2. The 1-sec peak
photon flux measured from T-0.16 sec in the 15-150 keV band
is 1.0 +- 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/669319/BA/