TITLE: GCN CIRCULAR NUMBER: 6966 SUBJECT: GRB 071021, Swift-BAT refined analysis DATE: 07/10/21 19:33:04 GMT FROM: Scott Barthelmy at NASA/GSFC L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+472 sec from recent telemetry downlinks, we report further analysis of BAT GRB 071021 (trigger #294974) (Sakamoto, et al., GCN Circ. 6958). The BAT ground-calculated position is RA, Dec = 340.573, 23.764 deg, which is RA(J2000) = 22h 42m 17.6s Dec(J2000) = 23d 45' 49" with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 78%. The mask-weighted light curve shows a slow rise starting at ~T-30 sec and peaking around T+85 sec. The remaining portion of the lightcurve is consistant with either a low-level constant emission out to ~T+225 sec or with a decline to background around T+150 sec and then another weak peak from ~T+180 to ~T+220 sec. This latter interpretation is consistant with a small flare in the XRT afterglow lightcurve around T+220 sec. T90 (15-350 keV) is 225 +- 10 sec (estimated error including systematics). The time-averaged spectrum from T-31.4 to T+252.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.70 +- 0.21. The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+87.32 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. This burst has several characteristics which are typical of high redshift bursts. Its duration is long (T90 = 225 sec) with relatively few (two) significant peaks. The 1-s peak flux is < 1.0 ph/cm2/s and the power-law photon index (1.70) is < 2.