TITLE: GCN CIRCULAR NUMBER: 16768 SUBJECT: GRB 140903A: Swift-BAT refined analysis DATE: 14/09/04 01:33:48 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings, N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-61 to T+159 sec from the recent telemetry downlink, we report further analysis of BAT GRB 140903A (trigger #611599) (Cummings, et al., GCN Circ. 16763). The BAT ground-calculated position is RA, Dec = 238.021, 27.608 deg which is RA(J2000) = 15h 52m 05.0s Dec(J2000) = +27d 36' 27.6" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 83%. The mask-weighted light curve shows a single FRED peak. T90 (15-350 keV) is 0.30 +- 0.03 sec (estimated error including systematics). The time-averaged spectrum from T-0.01 to T+0.35 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.99 +- 0.12. The fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.33 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. This burst was short but we note that it was not particularly hard. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/611599/BA/