TITLE: GCN CIRCULAR NUMBER: 43487 SUBJECT: GRB 260120B: Swift/UVOT Detection DATE: 26/01/21 14:04:46 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and M. Ferro (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 260120B 149 s after the BAT trigger (Ferro et al., GCN Circ. 43479). A fading source consistent with the optical counterpart position given by Wu et al., (GCN Circ. 43483) and also the enhanced XRT position (Goad et al., GCN Circ. 43484) is detected in the initial UVOT exposures. 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 149 299 147 18.38 ± 0.06 white 588 776 35 >19.4 v 637 657 19 >17.4 b 563 755 39 >18.7 u 307 557 246 18.80 ± 0.14 w1 686 705 19 >17.4 m2 661 681 19 >17.1 w2 613 633 19 >17.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.063 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/43487. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...