GCN Circular 22004
A. A. Breeveld (UCL-MSSL) and M. H. Siegel (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 171010A 69338 s after the LAT trigger (Omodei et al., GCN Circ. 21985). A afterglow (Thorstensen and Halpern, GCN Circ. 21987, Izzo and Malesani, GCN Circ. 21988, Guidorzi et al., GCN Circ. 21991, Malesani et al., GCN Circ. 22000, Harita et al., GCN Circ. 22001) is detected in the initial UVOT exposures. However it is not possible to distinguish this source from the position of the Pan-STARRS source given in Izzo and Malesani (GCN Circ. 21988). The source magnitude is not changing significantly within this observation. Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the summed exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 69338 80991 4818 18.84 �� 0.02 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.15 in the direction of the burst (Schlegel et al. 1998).