TITLE: GCN CIRCULAR NUMBER: 14279 SUBJECT: GRB 130306A: Swift-BAT refined analysis DATE: 13/03/09 01:15:33 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), A. Lien (NASA/GSFC/ORAU). T. Sakamoto (GSFC/UMBC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. H. Siegel (PSU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-160 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 130306A (trigger #550457) (Siegel, et al., GCN Circ. 14266). The BAT ground-calculated position is RA, Dec = 279.475, -11.682 deg, which is RA(J2000) = 18h 37m 54.1s Dec(J2000) = -11d 40' 55.0" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 11%. This burst was already active when it came into the BAT FoV during a slew at T-160 sec. There were several peaks until ~T-130 sec, then a long relatively smooth decay out past T+900 sec (when the data ends). The time-averaged spectrum from T-159.5 to T+154.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.95 +- 0.05. The 1-sec peak photon flux (during the period of BAT viewing) measured from T-152.73 sec in the 15-150 keV band is 7.3 +- 0.8 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/550457/BA/