TITLE: GCN CIRCULAR NUMBER: 16186 SUBJECT: GRB 140428A: Swift-BAT refined analysis DATE: 14/04/29 19:57:28 GMT FROM: Amy Lien at GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), D. Kocevski (NASA/GSFC/ORAU) A. Y. Lien (NASA/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+602 sec from the recent telemetry downlink, we report further analysis of BAT GRB 140428A (trigger #597519) (Kocevski et al., GCN Circ. 16177). The BAT ground-calculated position is RA, Dec = 194.365, 28.331 deg which is RA(J2000) = 12h 57m 27.5s Dec(J2000) = +28d 19' 53.4" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 70%. The mask-weighted light curve shows a multi-peaked structure starts at ~T-14 s and ends at ~T+6 s. The structure contains two main peaks at ~T-4 s and ~T+2 s. T90 (15-350 keV) is 17.42 +- 5.90 sec (estimated error including systematics). The time-averaged spectrum from T-14.19 to T+5.82 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.54 +- 0.26. The fluence in the 15-150 keV band is 3.4 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.30 sec in the 15-150 keV band is 0.6 +- 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/597519/BA/