TITLE: GCN CIRCULAR NUMBER: 9289 SUBJECT: GRB 090429A: Swift-BAT refined analysis DATE: 09/04/29 11:56:38 GMT FROM: Scott Barthelmy at NASA/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), C. B. Markwardt (GSFC/UMD), 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-61 to T+302 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090429A (trigger #350853) (Markwardt, et al., GCN Circ. 9280). The BAT ground-calculated position is RA, Dec = 90.573, -52.389 deg, which is RA(J2000) = 06h 02m 17.5s Dec(J2000) = -52d 23' 19.0" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a relatively smooth structure with a couple overlapping peaks starting at ~T-12 sec and peaking at T_zero. The main peak ends around T+40 sec with a long weak tail extending out to ~T+200 sec. T90 (15-350 keV) is 188 +- 37 sec (estimated error including systematics). The time-averaged spectrum from T-10.8 to T+203.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.55 +- 0.22. The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band is 0.6 +- 0.1 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/350853/BA/