TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3371 SUBJECT: GRB 050505: Further Swift UVOT observations. DATE: 05/05/06 14:17:46 GMT FROM: Simon Rosen at MSSL-UCL S. Rosen (MSSL), C. Hurkett (Leicester), S. Holland (GSFC), P. Roming (PSU), A. Blustin (MSSL), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team Further to the initial Swift UVOT results (Rosen et. al. 3367) we report the results of co-added, deeper exposures of GRB 050505 with the Swift Ultra-Violet/Optical Telescope (UVOT) on May 06, 2005. We detect no source at the Keck determined location (Cenko et al, GCN 3366) in any of the UVOT filters with the following 5 sigma and 3 sigma limits (in 6" radius apertures) Filter Lim_Mag Lim_mag Total duration (s) T_range (s) 5sigma 3sigma V 19.82 20.35 2527 2807 - 28543 B 20.50 21.04 1999 3236 - 26917 U 20.26 20.84 2890 3132 - 22757 UVW1 20.81 21.36 1999 3029 - 22040 UVM2 21.13 21.68 2422 2924 - 21132 UVW2 21.27 21.83 1997 3342 - 27826 T_range is since the BAT trigger time (Hullinger et al. 3364). The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration. We note that for the estimated redshift of 4.1 - 4.3 (GCN 3368), the Lyman limit lies between the UVOT B and V filters - the lack of a UVOT detection in V may be significant, depending on the brightness of the source detected by Keck and the true redshift. This message may be cited.