TITLE: GCN CIRCULAR NUMBER: 14887 SUBJECT: GRB 130612A: Swift/UVOT Detection DATE: 13/06/12 17:42:22 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (MSSL-UCL) and J. L. Racusin (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130612A 94 s after the BAT trigger (Racusin et al., GCN Circ. 14874). A fading source consistent with the XRT position (Beardmore et al. GCN Circ. 14884) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 17:19:10.58 = 259.79408 (deg.) Dec (J2000) = +16:43:11.9 = 16.71996 (deg.) with an estimated uncertainty of 0.53 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 94 185 89 18.97 ± 0.07 v 763 7763 549 >20.6 b 688 13692 1307 >21.3 u 664 1655 117 19.68 ± 0.24 w1 639 18651 2143 >21.6 m2 614 17743 1406 >21.6 w2 738 7559 549 >21.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.08 in the direction of the burst (Schlegel et al. 1998).