TITLE: GCN CIRCULAR NUMBER: 23443 SUBJECT: GRB 181123B: Swift-BAT lag analysis and search for extended emission DATE: 18/11/24 03:11:55 GMT FROM: Amy Lien at GSFC J. P. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC) report: We report the spectral lag analysis and the search for extended emission for GRB 181123B (Lien et al., GCN Circ. 23432). Using the 8-ms binned light curve, the spectral lag of the short pulse is 6 (+11, -11) ms for the 100-350 keV to 25-50 keV bands, and 10 (+14, -11) ms for the 50-100 keV to 15-25 keV bands. These lag values are consistent with a short GRB. The Bayesian block analysis using the mask-tagged light curves suggests that there may be a marginal (~ 3 sigma) extended emission that lasts until ~T+60 s.