TITLE: GCN CIRCULAR NUMBER: 7253 SUBJECT: GRB 080205: Swift/UVOT observations DATE: 08/02/05 16:16:32 GMT FROM: Samantha Oates at MSSL S.R. Oates (MSSL-UCL) and C.B Markwardt (CRESST/GSFC/UMD) report on behalf of the UVOT team. The Swift/UVOT observed the field of GRB 080205 (trigger #302506) starting 111 seconds after the BAT trigger (Markwardt et al., GCN Circ. 7250). We detect the optical afterglow at the position: RA (J2000) = 06:33:00.62 Dec (J2000) =+62:47:31.98 with an error of about 0.5". This is consistent with the position reported by Li et al.(GCN 7251) and lies within the revised XRT error circle (Osborne et al., GCN 7252). The optical afterglow initially brightens in the first few hundred seconds after the trigger and then begins to decay at around ~T+1000s. The afterglow is detected in the white and v filters only. The lack of detection in the b, u and uv filters suggests that this GRB is at a z ~ 4.0. The magnitudes and 3-sigma upper limits are listed: Filter Tstart(s) Tstop(s) Exp Magnitude -------------------------------------------------------------- white 111 211 98 20.37 +/- 0.28 (3.7-sigma) 864 964 98 19.76 +/- 0.17 (6.2-sigma) 5436 5636 196 20.59 +/- 0.25 (4.2-sigma) v 217 617 393 18.07 +/- 0.09 (11.4-sigma) 970 1370 393 19.02 +/- 0.20 (5.4-sigma) b 697 686 451 20.83 (3 sigma UL) u 672 6664 471 20.45 (3 sigma UL) uvw1 647 6458 286 20.13 (3 sigma UL) uvm2 622 7525 329 20.03 (3 sigma UL) uvw2 727 7279 452 20.39 (3 sigma UL) -------------------------------------------------------------- The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E_{B-V} = 0.091 mag in the direction of the burst (Schlegel et al. 1998).