GCN Circular 23440
K. Paterson and W. Fong (Northwestern) report: "We observed the field of the short-duration GRB 181123B (Lien et al., GCN 23432) with the Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) mounted on the 10-m Keck I telescope, starting on 2018 November 23 at 14:43:18 UT, 9.2 hours post-burst. We obtained 2100-sec of observations in the J-band in 1.0" seeing. In our combined stack, we identify a near-IR source consistent with the X-ray position of the afterglow (Evans et al., GCN 23433; Osborne et al., GCN 23434) and the Gemini optical source (Fong et al., GCN 23439). Calibrated to 2MASS, we estimate a preliminary brightness of J(AB) = 22.94 +/- 0.19 mag. At this point it is not possible to tell whether this source is point-like or extended. We thank the Keck Observatory staff, in particular Arina, Joel, Alessandro, Josh and Randy, for their assistance with planning and executing these observations."