TITLE: GCN CIRCULAR NUMBER: 14554 SUBJECT: GRB 130504A, Swift-BAT refined analysis DATE: 13/05/04 11:08:22 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130504A (trigger #555096) (Cummings, et al., GCN Circ. 14551). The BAT ground-calculated position is RA, Dec = 272.459, -16.320 deg which is RA(J2000) = 18h 09m 50.1s Dec(J2000) = -16d 19' 13.1" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. This position is 5.3 arcmin away from the automated flight position reported in GCN circular# 14551. The imaging interval selected onboard was not optimum. The refined error circle includes the position of the XRT afterglow candidate reported by D'Avanzo et al. in GCN circular# 14553, hence we believe that fading x-ray source to be the correctly identified afterglow of GRB 130504A. The mask-weighted light curve shows multiple weak peaks. T90 (15-350 keV) is 50 +- 10 sec (estimated error including systematics). The time-averaged spectrum from T-31.07 to T+36.84 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.52 +- 0.68, and Epeak of 84.5 +- 47.6 keV (chi squared 82.16 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.0 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T-0.06 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.41 +- 0.15 (chi squared 88.43 for 57 d.o.f.). 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/555096/BA/