H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), 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 160321A (trigger #680017)
(Stamatikos, et al., GCN Circ. 19211). The BAT ground-calculated position is
RA, Dec = 99.420, 5.753 deg which is
RA(J2000) = 06h 37m 40.7s
Dec(J2000) = +05d 45' 09.3"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
The mask-weighted light curve shows a single-pulse structure that starts
at ~ T0-22 sec, peaks at ~ T+2 sec, and ends at ~ T+23 sec.
T90 (15-350 keV) is 33.6 +- 4.8 sec (estimated error including systematics).
The time-averaged spectrum from T-20.9 to T+19.0 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.89 +- 0.19. The fluence in the 15-150 keV band is 5.3 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+2.17 sec in the 15-150 keV band
is 0.5 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
Based on the ground analysis result, this event is very likely a GRB.
However, given that it is on the Galactic Plane (lat = -0.43 deg.),
we cannot rule out a galactic origin. We note that the BAT time averaged
spectrum is soft but still in the typical range for BAT GRBs.
The results of the batgrbproduct analysis are available at