TITLE: GCN CIRCULAR NUMBER: 6225 SUBJECT: GRB 070328, Swift-BAT refined analysis DATE: 07/03/28 07:49:48 GMT FROM: Craig Markwardt at NASA/GSFC/UMD M. Stamatikos (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-120 to T+183 sec from the recent telemetry downlink, we report further analysis of BAT GRB 070328 (trigger #272773) (Markwardt et al., GCN Circ. 6224). The BAT ground-calculated position is RA, Dec = 65.110, -34.077 deg which is RA(J2000) = 4h 20m 26.4s Dec(J2000) = -34d 4' 38.9" with an uncertainty of 0.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask weighted light curve shows a burst profile which consists of a rise starting at T-10, multiple spikes peaking between T+0 and T+22, and a gradual decay detected out to T+140. T90 (15-350 keV) is 69 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-8.5 to T+133 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.26 +- 0.04. The fluence in the 15-150 keV band is 8.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.78 sec in the 15-150 keV band is 4.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level.