TITLE: GCN CIRCULAR NUMBER: 17263 SUBJECT: GRB 150101A: Swift/UVOT Upper Limits DATE: 15/01/01 16:27:00 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and A. Vargas (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150101A 65 s after the BAT trigger (Vargas et al., GCN Circ. 17261). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 17262) 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) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 65 215 147 >21.4 u_FC 277 527 246 >20.6 white 65 1524 392 >22.1 v 607 1574 117 >20.1 b 533 1500 97 >20.4 u 277 1475 324 >21.0 w1 656 1451 97 >19.4 m2 631 1425 97 >19.9 w2 583 1550 117 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.52 in the direction of the burst (Schlegel et al. 1998).