TITLE: GCN CIRCULAR NUMBER: 6404 SUBJECT: GRB 070509: Swift/UVOT Upper Limits DATE: 07/05/10 16:00:38 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) and L. Vetere (PSU) report on the behalf of the Swift UVOT team: The Swift/UVOT observed the field of GRB 070509 starting 73 s after the BAT trigger (Vetere et al. 2007, GCN Circ. 6394). We do not find any source, in any of the UVOT observations, inside the refined XRT error circle (Vetere et al., 2007 GCN Circ. 6400). The 3-sigma upper limits for detecting a source anywhere inside the refined XRT error circle in the co-added frames are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ----------------------------------------------------------------- V 179 6074 1003 20.6 B 657 1468 39 18.6 U 633 1443 58 18.4 UVW1 609 1419 58 18.0 UVM2 584 6085 65 17.5 UVW2 686 5869 236 19.3 White 73 1482 225 21.1 ----------------------------------------------------------------- The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.14 mag towards the direction of the burst (Schlegel et al. 1998).