TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5506 SUBJECT: GRB 060904: TAROT optical observations DATE: 06/09/04 02:51:49 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 060904 detected by SWIFT (trigger 227996) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. First image was acquired 26.8s after the GRB trigger (9.4s after the notice). The field elevation decreased from 10 degrees above horizon and weather conditions were excellents. First image was acquired during the prompt phase. Date of trigger : t0 = 2006-09-04T01:03:21.600 First image is 60.0 exposure trailed. No OT is visible in the XRT error box (Grupe et al. GCNC 5502) t0+26.8s to t0+86.8s : R > 16.0 Second image is 30.0 exposure. No OT is visible: t0+93.7s to t0+123.7s : R > 17.3 We co-added a series of exposures. No OT is visible: t0+93.7s to t0+376.2s : R > 19.5 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon= 71.6566 lat=+50.2105 and the galactic extinction in R band is 0.0 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited.