TITLE: GCN CIRCULAR NUMBER: 7677 SUBJECT: GRB 080503, Swift-BAT lag and time-resolved spectral analysis DATE: 08/05/04 18:39:40 GMT FROM: Scott Barthelmy at NASA/GSFC 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 7665 & 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 7673, 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.