TITLE: GCN CIRCULAR NUMBER: 15022 SUBJECT: GRB 130722A: Swift/UVOT Detection DATE: 13/07/23 02:38:51 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130722A 120 s after the BAT trigger (Troja et al., GCN Circ. 15013). A decaying source consistent with the optical position (Melandri et al. GCN Circ. 15015) is detected in the initial UVOT exposures. As noted by Melandri et al., there is a catalogued source near the position of the optical afterglow. The magnitudes and uncertainties reported below have been adjusted to accommodate the possibility that the nearby source accounts for all or none of the UVOT count rate observed at late times. The preliminary UVOT position is: RA(J2000) = 17:22:36.47 = 260.65196 DEC(J2000) = -02:58:21.6 = -2.97268 with an estimated uncertainty of 0.7 arcsec (radius, 90% confidence). The uncertainty has been adjusted slightly due to the possible contamination of the nearby source by up to 10%. The preliminary detection 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_FC 120 270 147 19.6 (+0.12/-0.20) v 4209 5844 393 >19.7 b 3594 17728 2039 >20.9 u 332 16943 2059 >21.0 w1 4619 16030 1218 >21.2 w2 4004 5640 393 >21.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.63 in the direction of the burst (Schlegel et al. 1998).