TITLE: GCN CIRCULAR NUMBER: 22566 SUBJECT: GRB 180329B: Swift-BAT refined analysis DATE: 18/03/30 13:57:48 GMT FROM: Amy Lien at GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. L. Racusin (NASA/GSFC), 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 180329B (trigger #819490) (Racusin et al., GCN Circ. 22558). The BAT ground-calculated position is RA, Dec = 82.905, -23.694 deg which is RA(J2000) = 05h 31m 37.2s Dec(J2000) = -23d 41' 39.8" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 15%. The mask-weighted light curve shows a triple-peaked structure, with the first peak running from T-10 to T+40 sec, and the second peak from T+130 to T+160 sec. This is followed by a much weaker, softer peak from T+160 to T+280 sec. T90 (15-350 keV) is 210.0 +- 44.0 sec (estimated error including systematics). The time-averaged spectrum from T-9.91 to T+230.39 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.97 +- 0.56, and Epeak of 48.6 +- 9.1 keV (chi squared 54.64 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.3 +- 0.3 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T+1.56 sec in the 15-150 keV band is 1.4 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.93 +- 0.12 (chi squared 65.32 for 57 d.o.f.). 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/819490/BA/