TITLE: GCN CIRCULAR NUMBER: 42959 SUBJECT: GRB251129A/EP251129a: Swift UVOT detection DATE: 25/12/02 18:31:14 GMT FROM: Paul Kuin at MSSL <npkuin@gmail.com> N.P.M. Kuin (UCL-MSSL) and B. Cenko (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of GRB 251129A 16.8 ks after the SVOM trigger (Tan et al., GCN Circ. 42877). GRB251129A was also detected by the EP (Wu et al, GCN Circ. 16828). The optical afterglow consistent with the SVOM/COLIBRI position (Angulo et al. GCN Circ. 42880; Watson, GCN Circ. 42883) 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) are:: Filter T_start(s) T_stop(s) Exp(s) Mag white 16828 17147 315 19.63 +/- 0.07 white 27564 28089 502 19.69 +/- 0.12 white 111007 117142 1044 20.22 +/- 0.12 white 227072 234439 2745 20.92 +/- 0.17 u 16503 16823 315 20.06 +/- 0.30 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.025 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42959. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...