TITLE: GCN CIRCULAR NUMBER: 8171 SUBJECT: GRB 080903: TAROT Calern observatory optical observations DATE: 08/09/03 03:45:24 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 080903 detected by SWIFT (trigger 323542) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 29.1s after the GRB trigger (11.4s after the notice). The elevation of the field increased from 38 degrees above horizon and weather conditions were excellents. The date of trigger : t0 = 2008-09-03T01:12:23.3 The first image is trailed with a duration of 60.0s (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT at the XRT position provided by Grupe et al. (GCNC 8169): t0+29.1s to t0+89.1s : R > 17.1 The second image is 30.0s exposure in tracking mode: t0+95.9s to t0+125.9s : R > 18.2 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=160.7489 lat=+11.6608 and the galactic extinction in R band is 0.6 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited.