TITLE: GCN CIRCULAR NUMBER: 18382 SUBJECT: GRB 151001B: Swift-BAT refined analysis DATE: 15/10/02 13:09:51 GMT FROM: Scott Barthelmy at NASA/GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 151001B (trigger #657321) (Krimm, et al., GCN Circ. 18374). The BAT ground-calculated position is RA, Dec = 336.974, 64.637 deg, which is RA(J2000) = 22h 27m 53.7s Dec(J2000) = +64d 38' 13.5" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 28%. The mask-weighted light curves shows several overlapping peaks starting at ~T-40 sec, peaking at ~T+50 sec, and ending at ~T+150 sec. T90 (15-350 keV) is 109 +- 17 sec (estimated error including systematics). The time-averaged spectrum from T-23.3 to T+97 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.12 +- 0.27. The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+47.47 sec in the 15-150 keV band is 0.5 +- 0.3 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/657321/BA/