TITLE: GCN CIRCULAR NUMBER: 13535 SUBJECT: GRB 120728A, Swift-BAT refined analysis DATE: 12/07/29 16:13:33 GMT FROM: Hans Krimm at NASA-GSFC C. B. Markwardt (GSFC), 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), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (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 120728A (trigger #529021) (Cummings, et al., GCN Circ. 13525). The BAT ground-calculated position is RA, Dec = 137.085, -54.437 deg which is RA(J2000) = 09h 08m 20.3s Dec(J2000) = -54d 26' 12.4" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 13%. The mask-weighted light curve shows a broad FRED-like peak of total duration ~25 seconds with three subsidiary peaks superimposed. The T90 (15-350 keV) is 22.06 +- 2.59 sec (estimated error including systematics). The time-averaged spectrum from T+0.56 to T+26.46 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.13. The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+12.12 sec in the 15-150 keV band is 2.4 +- 0.5 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/529021/BA/