GCN Circular 19393

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),
D. Malesani (DARK/NBI), C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160504A (trigger #685124)
(Malesani, et al., GCN Circ. 19382
Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 170.073, 56.002 deg which is
RA(J2000) = 11h 20m 17.5s
Dec(J2000) = +56d 00' 05.7"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 88%.

The mask-weighted light curve shows that the main emission starts at T-40 sec, 
has a very broad profile, peaks near T+0 sec and ends by T+30 sec. T90 (15-350 
keV) is 53.9 +- 6.0 sec (estimated error including systematics). We have 
concluded that a soft spike in the light curve of ~10 msec duration at T-135.5 
sec is of instrumental and not astrophysical origin.  Our analysis therefore 
excludes the time before T-135 sec.

The time-averaged spectrum from T-42.3 to T+16.2 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.88 +- 0.20. The fluence in the 15-150 keV band is 7.3 +- 0.9 x 10^-7erg/cm2.
The 1-sec peak photon flux measured from T+0.51 sec in the 15-150 keV band
is 0.7 +- 0.1 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/685124/BA/