TITLE: GCN CIRCULAR NUMBER: 35777 SUBJECT: GRB 240222A: Swift/UVOT Upper Limits DATE: 24/02/22 22:34:59 GMT FROM: Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk> S. R. Oates (Lancaster. U) 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 240222A 98s after the BAT trigger (D'Avanzo et al., GCN Circ 35770). No optical afterglow consistent with X-ray (D'Avanzo et al., GCN Circ. 35770) position is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 98 1192 205 >20.9 v 642 1068 58 >18.5 b 567 1168 58 >19.5 u 311 1142 285 >20.0 uvw1 691 1118 39 >18.3 uvm2 666 861 39 >18.0 uvw2 617 1044 58 >18.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.16 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/35777. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...