TITLE: GCN CIRCULAR NUMBER: 42355 SUBJECT: GRB 251017A: Swift/UVOT Detection DATE: 25/10/18 12:06:08 GMT FROM: s.shilling@lancaster.ac.uk S. P. R. Shilling (Lancaster U.) and R. Gupta (NASA GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251017A 98 s after the BAT trigger (Gupta et al., GCN Circ. 42322). A source consistent with the enhanced XRT position (Goad et al., GCN Circ. 42326) 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 121 270 147 20.09 +/- 0.22 v 98 1234 109 >18.8 b 588 5138 83 >19.6 u 333 5126 501 >20.3 w1 712 4921 255 >18.5 w2 811 1384 58 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.108 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42355. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...