TITLE: GCN CIRCULAR NUMBER: 9546 SUBJECT: GRB 090621A: Swift-BAT refined analysis DATE: 09/06/22 01:14:19 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), P.A. Curran (MSSL-UCL), 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-239 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090621A (trigger #355303) (Curran, et al., GCN Circ. 9540). The BAT ground-calculated position is RA, Dec = 10.987, 61.938 deg, which is RA(J2000) = 00h 43m 56.8s Dec(J2000) = +61d 56' 17.6" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 77%. The mask-weighted light curve shows two small precursor peaks starting at ~T-30 sec, peaking at ~T-20 and T+10 sec, and returning to background at ~T+100 sec. Then the mmain emission starts at ~T+210 sec, peaks at ~T+240 and T+265 sec, and returns to background around T+350 sec. T90 is not possible because of a lack of the complete set of event by event data set for this burst. This also prevents giving spectral results.