TITLE: GCN CIRCULAR NUMBER: 15443 SUBJECT: GRB 131103A: Swift/UVOT Detection DATE: 13/11/04 15:51:58 GMT FROM: Frank Marshall at GSFC N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), and J. R. Cummings (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 131103A 87 s after the BAT trigger (Cummings et al., GCN Circ. 15440). A decaying source consistent with the XRT position (Goad et al. GCN Circ. 15442) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 23:15:40.55 = 348.91894 (deg.) Dec (J2000) = -44:38:25.4 = -44.64040 (deg.) with an estimated uncertainty of 0.60 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 87 237 147 19.41 +/- 0.13 white 19290 19893 599 21.45 +/- 0.17 v 629 12543 1173 >20.0 b 554 25509 1664 21.64 +/- 0.23 u 299 549 246 18.93 +/- 0.13 w1 678 24073 1116 >20.6 w2 6741 6941 197 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).