TITLE: GCN CIRCULAR NUMBER: 9979 SUBJECT: GRB 090929B, Swift-BAT refined analysis DATE: 09/09/30 21:04:27 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), C. Pagani (PSU), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+691 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090929 (trigger #371050) (Pagani, et al., GCN Circ. 9963). The BAT ground-calculated position is RA, Dec = 117.712, -0.645 deg which is RA(J2000) = 07h 50m 50.9s Dec(J2000) = -00d 38' 41.2" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 63%. The mask-weighted lightcurve shows many peaks interspersed with intervals with no detected flux, from T-10 to T+380 sec when the source left the coded field of view due to a observing constraint. There may have been small and/or low-energy peaks beyond this time. The largest peak was at about T+30 to T+40 sec. T90 (15-350 keV) was 360 +- 20 sec (estimated error including systematics). The time-averaged spectrum from T-9.8 to T+371.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.08. The fluence in the 15-150 keV band is 5.9 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+30.67 sec in the 15-150 keV band is 3.3 +- 0.2 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/371050/BA/