{
  "bibcode": "2005GCN..3720....1K",
  "body": "Klotz, A. (CESR-OMP), Boer M. (OHP), and Atteia, J.L. (LAT-OMP) report:\n\nWe imaged the entire field of GRB 050730 detected by SWIFT (Holland et al. GCNC\n3704) with the TAROT robotic telescope (D=25cm) located at the Calern\nobservatory, France. Observations started 7.5 seconds after the GCN notice (and\n66.3 s after the GRB). The field had an elevation of\n29 degrees above horizon at the begining of the observations and then decreased.\n\nThe first three images taken between 2005-07-30T19:59:29.53 (GRB +\n66.3s) and 2005-07-30T20:00:27.38 (GRB + 124.2s) were co-added. The afterglow is\nperhaps detected very marginally. The magnitude is estimated to be\nR=15.5 +/- 0.4 comparing with the USNO-B1 nearby stars. This magnitude should be\nrather considered as an upper limit.\n\nA second set of three images taken between 2005-07-30T20:00:33.60 (GRB +\n130s) and 2005-07-30T20:01:46.25 (GRB + 203s) we co added.\nThe afterglow is not detected, suggesting R>15.9 comparing with the\nUSNO-B1 nearby stars.\n\nCo addition of the six first images (GRB + 66.3s to 203s) shows the afterglow\nmeasured to be R=16.24 +/- 0.41.\n\nLater images were taken with longer exposure times and were co added to measure\nthe afterglow magnitude with a reasonable accuracy:\n\nt=GRB + 26.79 min  R=17.00 +/- 0.41\nt=GRB + 37.61 min  R=17.30 +/- 0.44\nt=GRB + 48.61 min  R=17.34 +/- 0.37\nt=GRB + 61.20 min  R=17.92 +/- 0.42\nt=GRB + 78.47 min  R=17.54 +/- 0.39\nt=GRB + 97.40 min  R=18.74 +/- 0.53\n\nThis later series gives a decay index of 0.89 +/- 0.38.\n\nAn extrapolation towards the early measurement shows that a break or a\nre-brightening should occured considering our R=16.24 measurement at t=GRB +\n2.31 min.\n\nFurther informations (light curve and images) on:\nhttp://www.cesr.fr/~klotz/grb050730\n\nThis message can be cited.\n\n\n--\nMichel Boer\nObservatoire de Haute Provence\nF - 04870 Saint Michel l'Observatoire\n04 92 70 64 59 - Michel.Boer@oamp.fr",
  "circularId": 3720,
  "createdOn": 1122884332000,
  "email": "Michel.Boer@oamp.fr",
  "subject": "GRB 050730: early TAROT optical observations",
  "submitter": "Michel Boer at Obs Haute Prov.  <Michel.Boer@oamp.fr>",
  "eventId": "GRB 050730"
}