TITLE: GCN CIRCULAR NUMBER: 18110 SUBJECT: GRB 150801B: Swift-BAT refined analysis DATE: 15/08/02 19:47:20 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift S. D. Barthelmy (GSFC), J. R. Cummings (CPI), 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), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150801B (trigger #650977) (Sbarufatti, et al., GCN Circ. 18104). The BAT ground-calculated position is RA, Dec = 82.961, -5.374 deg which is RA(J2000) = 05h 31m 50.7s Dec(J2000) = -05d 22' 28.0" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 62%. The mask-weighted light curve shows two widely separated episodes. The first episode was about 40 seconds long starting at about T-20 seconds. There were two prominent overlapping FRED peaks at T0 and T+10 seconds, followed by a return to background level. The second episode became detectable in BAT at about T+330 seconds and returned to background about T+450 seconds. There were two smaller cusp-shaped peaks at T+370 and T+390 seconds, about 10 and 7 seconds long. The peaks between 330 and 450 seconds are at the same time as bright X-ray flares detected by XRT. T90 (15-350 keV) was 426 +- 30 sec (estimated error including systematics). The time-averaged spectrum from T-30.16 to T+433.94 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.84 +- 0.14. The fluence in the 15-150 keV band is 3.1 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+9.32 sec in the 15-150 keV band is 2.5 +- 0.2 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/650977/BA/