TITLE: GCN CIRCULAR NUMBER: 14857 SUBJECT: GRB 130609B: Swift/UVOT Observations DATE: 13/06/10 16:46:41 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130609B 85 s after the BAT trigger (Krimm et al., GCN Circ. 14841). A fading source consistent with the XRT position (Goad et al. GCN Circ. 14847) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 03:35:05.11 = 53.77128 (deg.) Dec (J2000) = -40:10:26.7 = -40.17409 (deg.) with an estimated uncertainty of 0.50 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 first and second orbit exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 84 234 147 15.47+-0.02 white 577 1891 283 17.36+-0.03 white 6046 7681 393 18.39+-0.05 v 799 1941 136 16.89+-0.09 v 6457 6657 196 18.00+-0.15 b 552 1866 136 17.32+-0.06 b 5841 7476 393 18.46+-0.09 u (fc) 297 546 245 16.31+-0.04 u 700 1841 116 17.15+-0.08 u 5636 7271 393 18.15+-0.09 uvw1 676 1816 136 17.61+-0.12 uvw1 5432 7067 393 18.75+-0.15 uvm2 823 1791 116 19.12+-0.35 uvm2 6662 6861 196 >19.66 uvw2 603 1916 116 >19.51 uvw2 6252 7855 362 >20.39 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).