TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3073 SUBJECT: GRB 050306: TAROT optical observations DATE: 05/03/07 11:28:41 GMT FROM: Michel Boer at Obs Haute Prov. Klotz, A., Boer M. (OHP), Atteia, J.L., and G. Stratta (LATT) report: We imaged the entire field of GRB 050306 (cf. Markwardt et al. GCNC 3071) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. Observations started 90 seconds after the begining of the burst. The source was at an elevation of 15 degrees above the horizon. The Moon did not rise during the observation, though the burst source location was 19 deg from it. Nevertheless, haze was present, resulting in a loss of sensitivity. No new source was detected after a comparison with the DSS2 R image. We summarize below the limiting magnitude obtained by TAROT : Beg. burst event 2005-03-06 03:33:12 UT (from GCNC 3071) End. burst event 2005-03-06 03:36:12 UT (from GCNC 3071) Date from to Rmag Remarks 2005-03-06 03:35:19 03:35:49 >11 during prompt emission 2005-03-06 03:36:42 03:40:32 >13 2005-03-06 03:41:37 03:43:31 >14.4 6 min after the end of prompt emission 2005-03-06 03:44:32 03:45:40 >13 This message is citable.