TITLE: GCN CIRCULAR NUMBER: 12598 SUBJECT: GRB 111123A, Swift-BAT refined analysis DATE: 11/11/26 00:24:19 GMT FROM: Takanori Sakamoto at NASA/GSFC H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), 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+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 111123A (trigger #508319) (Stamatikos, et al., GCN Circ. 12587). The BAT ground-calculated position is RA, Dec = 154.845, -20.639 deg which is RA(J2000) = 10h 19m 22.9s Dec(J2000) = -20d 38' 19.9" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%. The mask-weighted light curve shows two episodes. The first episode is starting at T-10 sec, and peaking at T+10 sec with possible two or three overlapping pulses. The second episode shows a gradual increases after the end of the initial episode, peaks at T+150 sec, and ends at T+170 sec. The low level emission continues up to T+~300 sec. T90 (15-350 keV) is 290.0 +- 88.1 sec (estimated error including systematics). The time-averaged spectrum from T-8.7 to T+481.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.68 +- 0.07. The fluence in the 15-150 keV band is 7.3 +- 0.3 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+146.30 sec in the 15-150 keV band is 0.9 +- 0.1 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/508319/BA/