[vsnet-grb-info 18013] GRB 160525A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19461
SUBJECT: GRB 160525A: Swift-BAT refined analysis
DATE:    16/05/25 12:09:38 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

T. N. Ukwatta (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), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+903 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 160525A (trigger #687492)
(Stamatikos, et al., GCN Circ. 19458).  The BAT ground-calculated position is
RA, Dec = 103.575, -0.199 deg, which is 
   RA(J2000)  =  06h 54m 17.9s 
   Dec(J2000) = -00d 11' 55.6" 
with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.
 
The mask-weighted light curve shows a weak peak starting at ~T+5 sec and
ending at ~T+65 sec.
 
The time-averaged spectrum from T+0.00 to T+64.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.58 +- 0.54.  The fluence in the 15-150 keV band is 1.9 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band
is 0.06 +- 0.02 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

Given the low significance of the peak in the image domain (5.2 sigma)
in the ground analysis and the lack of XRT data (Sun constrained),
it is not possible to know with certainty if this is a GRB, but it seems likely.
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/687492/BA/