TITLE: GCN CIRCULAR NUMBER: 19275 SUBJECT: GRB 160410A: Swift/UVOT Detection DATE: 16/04/10 17:40:46 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and S. L. Gibson (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160410A 91 s after the BAT trigger (Gibson et al., GCN Circ. 19271). A source consistent with the initial UVOT position (Gibson et al. GCN Circ. 19271), the enhanced XRT position (Beardmore et al. GCN Circ. 19273), and the GROND position (Yates et al. GCN Circ. 19272) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 10:02:44.37 = 150.68488 (deg.) Dec (J2000) = +03:28:42.7 = 3.47853 (deg.) with an estimated uncertainty of 0.49 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 91 241 147 19.46 +/- 0.10 v 4867 6503 393 >19.7 b 4251 5887 393 >20.2 u 304 12411 866 20.50 +/- 0.20 w1 5277 11801 1082 >20.3 m2 5072 10893 1082 >20.8 w2 4662 6298 393 >20.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).