TITLE: GCN CIRCULAR NUMBER: 17275 SUBJECT: GRB 150103A: Swift/UVOT Upper Limits DATE: 15/01/04 04:04:17 GMT FROM: Lea Hagen at PSU L. M. Z. Hagen (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150103A 135 s after the BAT trigger (Hagen et al., GCN Circ. 17269). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 17272) 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) 135 284 147 >20.49 white 573 7047 618 >21.08 v 624 6018 293 >19.31 b 549 6841 471 >20.41 u (fc) 293 543 245 >19.66 u 698 6635 451 >19.95 uvw1 673 6429 471 >19.73 uvm2 648 6224 471 >19.54 uvw2 599 7179 417 >19.67 The magnitudes in the table are not corrected for the Galactic extinction due to the large, but uncertain, reddening of E(B-V) = 1.46 in the direction of the burst (Schlegel et al. 1998).