TITLE: GCN CIRCULAR NUMBER: 5744 SUBJECT: GRB 061021, Swift-BAT refined analysis DATE: 06/10/21 18:42:58 GMT FROM: Scott Barthelmy at NASA/GSFC D. Palmer (LANL), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Moretti (INAF-OAB), A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using the data set from T-240 to T+328 sec from recent telemetry downlinks, we report further analysis of BAT GRB 061021 (trigger #234905) (Moretti, et al., GCN Circ. 5743). The BAT ground-calculated position is RA,Dec = 145.146, -21.953 deg {9h 40m 35.0s, -21d 57' 10.4"} (J2000) +- 0.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 64%. The mask-weighted lightcurve shows a cusp-like peak starting at T+0 sec, peaking at T+2.6 sec, and exponetially tailling off to background at T+90 sec. T90 (15-350 keV) is 46 +- 1 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+59.9 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.31 +- 0.06. The fluence in the 15-150 keV band is 3.0 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.44 sec in the 15-150 keV band is 6.1 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.