TITLE: GCN CIRCULAR NUMBER: 30482 SUBJECT: GRB 210722A: Swift/UVOT Detection DATE: 21/07/23 13:46:11 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210722A 94 s after the BAT trigger (D'Avanzo et al., GCN Circ. 30475). A source consistent with the XRT position is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 01:48:07.28 = 27.03033 (deg.) Dec (J2000) = -06:20:49.7 = -6.34713 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). Preliminary detections 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 94 244 147 14.31 +/- 0.02 v 637 656 19 14.52 +/- 0.06 b 563 583 20 14.65 +/- 0.04 u 308 557 246 13.68 +/- 0.02 w1 686 705 20 14.08 +/- 0.06 w2 4908 4971 62 17.08 +/- 0.14 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.027 in the direction of the burst (Schlegel et al. 1998).