TITLE: GCN CIRCULAR NUMBER: 24817 SUBJECT: GRB 190613B: Swift/UVOT Detection DATE: 19/06/13 17:39:39 GMT FROM: Frank Marshall at Swift/UVOT F. E. Marshall (NASA/GSFC) and A. D'Ai (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190613B 106 s after the BAT trigger (D'Ai et al., GCN Circ. 24807). A source consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 24812) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 20:21:43.66 = 305.43191 (deg.) Dec (J2000) = -04:38:48.0 = -4.64666 (deg.) with an estimated uncertainty of 0.43 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 106 256 147 17.84 +/- 0.04 v 648 667 19 >18.0 b 574 594 19 >18.7 u 318 568 246 18.86 +/- 0.12 w1 697 717 19 >18.6 m2 672 692 19 >18.4 w2 624 643 19 >18.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998).