TITLE: GCN CIRCULAR NUMBER: 8365 SUBJECT: GRB 081012: Swift/UVOT analysis of initial observations DATE: 08/10/12 20:33:06 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL/UCL) and M.C. Stroh (PSU) report on behalf of the Swift UVOT team. The Swift UltraViolet/Optical Telescope (UVOT) began observations of GRB081012 (Swift BAT trigger number 331475, Stroh et al., GCN Circ. 8361), on October 12, 2008, at 14:02:28 ,52 minutes after the trigger. We do not detect any new source at the XRT position reported in GCN Circ. 8364 (Kennea et al.). The magnitude upper limits for detecting GRB081012 at the XTR position are given below for the first observations in the UVOT filters: Filter Tstart(s) Tstop(s) Exp(s) Magnitude uvw2 3125 3325 196.6 >20.09 (3-sigma UL) v 3329 3458 125.8 >19.12 (3-sigma UL) uvm2 4876 5076 196.6 >19.72 (3-sigma UL) uvw1 5082 5282 196.6 >19.94 (3-sigma UL) u 5287 5487 196.6 >20.00 (3-sigma UL) b 5492 5692 196.6 >20.33 (3-sigma UL) wh 5697 5713 15.7 >19.42 (3-sigma UL) The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected galactic reddening of E(B-V) = 0.023 in the direction of the burst (Schlegel et al. 1998).