TITLE: GCN CIRCULAR NUMBER: 22153 SUBJECT: GRB 171123A: Swift-BAT refined analysis DATE: 17/11/24 00:14:52 GMT FROM: Amy Lien at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U Leicester), H. A. Krimm (NSF/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-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171123A (trigger #791922) (Evans et al., GCN Circ. 22148). The BAT ground-calculated position is RA, Dec = 186.198, 32.503 deg which is RA(J2000) = 12h 24m 47.6s Dec(J2000) = +32d 30' 12.5" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 86%. The mask-weighted light curve shows a weak pulse that starts at ~T-1 s and ends at ~T+20 s, with a tail lasting till ~T+60 s. In addition, there is a weak precursor from ~T-25 s to ~T-20 s. T90 (15-350 keV) is 58.5 +- 27.1 sec (estimated error including systematics). The time-averaged spectrum from T-1.39 to T+60.29 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.35 +- 0.34. The fluence in the 15-150 keV band is 4.8 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.27 sec in the 15-150 keV band is 0.8 +- 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/791922/BA/