TITLE: GCN CIRCULAR NUMBER: 8064 SUBJECT: GRB 080804: Faulkes Telescope South observations DATE: 08/08/05 15:05:59 GMT FROM: Cristiano Guidorzi at INAF-OAB C. Guidorzi (INAF-OAB) and I. Steele (LJMU) on behalf of a larger collaboration report: On 2008 August 05 (12:44:12 UT) we began observing the field of GRB 080804 (Racusin et al. GCN Circ. 8057) with the Faulkes Telescope South using the R filter. In our coadded frame we detect the optical afterglow at the position fully consistent with that reported by Swift-UVOT (Racusin et al. GCN Circ. 8057) and slighly outside the error circle given by ROTSE-III (Rujopakarn et al. GCN Circ. 8056) which is 1.5 arcsec away. Telescope Filter T_mid[hr] Exposure[s] Mag ----------------------------------------------------------- FTS R 14.235 1200 21.6 +/- 0.1 ----------------------------------------------------------- The calibration was performed using the R2 magnitudes of several USNOB-1 catalogue field objects. The uncertainty reported above does not include the additional ~0.3 mag of the USNOB-1 catalogue. From the comparison with the value reported by UVOT we infer an average power-law decay index of ~0.7.