TITLE: GCN CIRCULAR NUMBER: 29555 SUBJECT: GRB 210217A: Swift/UVOT Detection DATE: 21/02/23 14:27:28 GMT FROM: Kira Simpson at PSU GRB 210217A: Swift/UVOT Detection K. K. Simpson (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210217A 103 s after the BAT trigger (Simpson et al., GCN Circ. 29521). A source consistent with the XRT position *** POSITION REFERENCE is GCN_Notice *** is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 06:30:19.90 = 97.58291 (deg.) Dec (J2000) = +68:43:30.6 = 68.72517 (deg.) with an estimated uncertainty of 0.46 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 103 253 147 18.80 +/- 0.06 u 315 508 190 18.64 +/- 0.11 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.102 in the direction of the burst (Schlegel et al. 1998).