GCN Circular 7677

Subject

GRB 080503, Swift-BAT lag and time-resolved spectral analysis

Event

Date

2008-05-04T18:39:40Z (18 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

T. Ukwatta (GWU), M. Stamatikos (GSFC/ORAU), T. Sakamoto (GSFC/UMBC),
J. Norris (U. of Denver), S. D. Barthelmy (GSFC)
(for the Swift-BAT team):
 
For GRB 080503 (Trigger 310785, GCNs 7665Loading...
 
  & 7673),
the spectral lag analysis of the data from T-1 sec to T+1 sec
(the initial spike), yields a lag of -13 +/- 9 msec for the
15-25 to 50-100 keV bands using lightcurve binnings of 4, 8 and 16 msec.
For the on-going emission (T+10 to T+220 sec), the signal is too weak
and lacking sufficient structure to yield a significant lag measurement.

Expanding on the total-burst spectral analysis in GCN 7673Loading...
 
 ,
we have divided the burst into an initial phase (T+0.0 to T+0.7 sec)
and the extended phase (T+10 to T+170 sec).  The simple power law fits are:
  Phase     PLI            Norm(@50keV)         Chi2/DoF
  Initial   1.59 +/-0.28  (8.15 +- 1.5)E-3      69/59
  Extended  1.91 +/-0.12  (1.19 +- 0.08)E-3     52/59
The units of Normalization are ph/cm2/s/keV.

This lag value plus the spectral results puts this burst
in the short hard burst category.