TITLE: GCN CIRCULAR NUMBER: 9641 SUBJECT: GRB 090709B, Swift-BAT refined analysis DATE: 09/07/09 23:02:32 GMT FROM: Hans Krimm at NASA-GSFC T. N. Ukwatta (GWU), 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), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 090709B (trigger #356912) (Marshall et al., GCN Circ. 9633). The BAT ground-calculated position is RA, Dec = 93.522, 64.081 deg which is RA(J2000) = 06h 14m 05.4s Dec(J2000) = +64d 04' 51.9" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 15%. The mask-weighted light curve shows a main peak beginning at T-5 seconds and continuing until T+10 sec. There are then two much weaker peaks at approximately T+25 and T+35 sec. At T+240 sec, a pre-planned spacecraft slew took the source out of the BAT FOV. T90 (15-350 keV) is 27.2 +- 6.6 sec (estimated error including systematics). The time-averaged spectrum from T-5.4 to T+35.9 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.51 +- 0.18. The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10-6 erg/cm2. The 1-sec peak photon flux measured from T+1.47 sec in the 15-150 keV band is 2.1 +- 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/356912/BA/