TITLE: GCN CIRCULAR NUMBER: 14862 SUBJECT: GRB 130609B, Swift-BAT refined analysis DATE: 13/06/10 21:39:05 GMT FROM: Hans Krimm at NASA-GSFC A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130609B (trigger #557828) (Krimm, et al., GCN Circ. 13841). The BAT ground-calculated position is RA, Dec = 53.776, -40.168 deg which is RA(J2000) = 03h 35m 06.2s Dec(J2000) = -40d 10' 04.0" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 43%. The mask-weighted light curve shows an initial complex of two main overlapping peaks with numerous subsidiary peaks, with strong emission between T-10 and T+50 sec and low-level emission between T-30 and T+120 sec. The highest points are at T+4 and T+18 sec. Then there is a second, weaker and softer pair of overlapping peaks between T+160 sec and T+220 sec. This second set of peaks is consistent with a flare seen in the Swift-XRT. T90 (15-350 keV) is 191.98 +- 2.44 sec (estimated error including systematics) We note that receipt of the full event data for GRB 130609B may reveal further late-time peaks and require a revision of the T90 estimate. We will report on the full data set in a later Circular. The time-averaged spectrum from T-7.84 to T+213.25 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.23 +- 0.04. The fluence in the 15-150 keV band is 1.6 +- 0.0 x 10^-05 erg/cm2. The 1-sec peak photon flux measured from T+16.78 sec in the 15-150 keV band is 8.5 +- 0.4 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/557828/BA/