TITLE: GCN CIRCULAR NUMBER: 42191 SUBJECT: GRB251007A: Swift/UVOT Detection DATE: 25/10/10 17:40:49 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18@psu.edu> M. H. Siegel (PSU) and E/ Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 251007A 79 s after the BAT trigger (Ambrosi et al., GCN Circ. 42146). A fading source consistent with the XRT position (Beardmore et al., GCN Circ. 42161) and the previously reported optical source (Wu et al., GCN Circ. 42154; Malesani et al., GCN Circ. 42158, Hu et al. GCN Circ 42174) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 08:32:42.39 = 128.17664 (deg.) Dec (J2000) = +21:48:46.3 = 21.81285 (deg.) with an estimated uncertainty of 0.45 arc sec. (radius, 90% confidence). Preliminary detections 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 80 229 146 18.42+/-0.08 white 17739 18156 406 >20.41 v 11939 39105 2335 >20.09 b 16827 17734 885 >20.39 u 291 418 124 19.11+/-0.36 uvm2 27913 39155 906 >20.29 uvw2 23059 34819 1506 >20.58 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.039 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/42191. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...