TITLE: GCN CIRCULAR NUMBER: 17338 SUBJECT: GRB 150120B: Swift/UVOT Upper Limits DATE: 15/01/21 13:36:09 GMT FROM: Margaret Chester at PSU GRB 150120B: Swift/UVOT Upper Limits M. M. Chester (PSU) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150120B 432 s after the BAT trigger (D'Elia et al., GCN Circ. 17314). No source consistent with the optical afterglow reported by Perley (GCN Circ. 17315) and Guidorzi et al. (GCN Circ. 17316) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 432 582 147 >19.9 white 432 1014 295 >20.5 white 7279 7479 197 >20.7 v 6254 19560 1278 >20.1 b 7074 25878 979 >20.9 u 6869 25353 1999 >21.0 w1 639 2670 214 >19.6 w1 6664 24440 2164 >21.0 m2 6459 20294 1996 >21.0 w2 1885 3036 124 >19.5 w2 7484 18646 1082 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.20 in the direction of the burst (Schlegel et al. 1998).