TITLE: GCN CIRCULAR NUMBER: 35366 SUBJECT: GRB 231215A: Swift/UVOT Detection DATE: 23/12/15 22:38:34 GMT FROM: Paul Kuin at MSSL <npkuin@gmail.com> N. P. M. Kuin (UCL-MSSL) 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 231215A 2733 s after the BAT trigger (D'Avanzo et al., GCN Circ. 35343). A source consistent with the XRT position (Goad et al., GCN Circ. 35357) is detected in the initial UVOT exposures. The burst was also detected by Fermi GBM (GCN Circ. 35344),Astrosat CZTI (Navaneeth et al., GCN Circ. 35352), and in the optical by Master (Lipunov et al., 35347), MONDY (Pankov et al. GCN Circ. 35349), MITSume Akeno (Sasada et al., GCN Circ. 35351), GROWTH-India (Wagh et al., GCN Circ 35354), BOOTES-4/MET (Hu et al., GCN Circ 35363), HMT-Nanshang (An et al. GCN Circ. 35353) and an upper limit from AKO (Odeh, GCN Circ. 36362). The preliminary UVOT position is: RA (J2000) = 00:38:57.52 = 9.73967 (deg.) Dec (J2000) = +57:38:50.5 = 57.64735 (deg.) with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence). 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 2733 2883 147 18.10 +/- 0.05 v 3713 3912 197 17.48 +/- 0.08 b 3096 3296 197 18.63 +/- 0.09 u 2891 3091 197 18.17 +/- 0.10 w1 4124 4323 197 19.57 +/- 0.31 m2 3918 4117 197 >19.4 w2 3507 3707 197 >19.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.506 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/35366. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...