TITLE: GCN CIRCULAR NUMBER: 38008 SUBJECT: GRB 241030B: Swift/UVOT Detection DATE: 24/10/31 12:56:29 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk> A. A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 241030B 162 s after the BAT trigger (Klingler et al., GCN Circ. 37981). The optical counterpart (Fu et al., GCN Circ. 37985; Odeh et al., GCN Circ. 37986; Moskvitin et al., GCN Circ. 37987; Brivio et al., GCN Circ. 37991; Moskvitin et.al GCN Circ. 37995 and Qui et al. GCN Circ. 37999) is detected in the initial UVOT exposure in the white filter only. 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 162 538 167 21.00 ± 0.30 v 395 4817 255 >19.4 b 494 857 58 >19.3 u 469 5380 203 >20.2 w1 444 5228 255 >21.1 m2 4822 5021 197 >19.7 w2 371 4612 255 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.204 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/38008. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...