GCN Circular 19276

T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), S. L. Gibson (U Leicester), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU),
D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from the recent telemetry downlinks,
we report further analysis of BAT short GRB 160410A (trigger #682269)
(Gibson, et al., GCN Circ. 19271
Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 150.695, 3.461 deg, which is 
   RA(J2000)  =  10h 02m 46.9s 
   Dec(J2000) = +03d 27' 40.3" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.
 
The mask-weighted light curve shows an initial spike starting at ~T-0.2 s
peaking at ~T+0.1 s with a decay out to ~T+2.5 s, then a greatly reduced
flux level portion out to ~T+9 s.  T90 (15-350 keV) is 8.2 +- 1.6 s
(estimated error including systematics).
 
The time-averaged spectrum from T+0.04 to T+9.60 s is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.93 +- 0.17.  The fluence in the 15-150 keV band is 7.8 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.04 sec in the 15-150 keV band
is 3.5 +- 0.3 ph/cm2/s.  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/682269/BA/

Using a 4-ms binned light curve for this bright burst, the lag of the initial pulse
(~T0 to ~T0+2 s) for the 100-350 keV to 25-50 keV bands is -3 (+/-7) ms
(with 1-sigma error) and for the 50-100 kev to 15-25 keV bands the lag is 8 (+/-14) ms.
These values are consistant with zero, thus confirming that this is a short GRB.
There is extended emission out to ~T+10 sec at ~0.038 counts/det/sec then dropping
to ~0.0055 counts/det/sec out to ~T+92 sec.