{
  "bibcode": "2012GCN.13739....1K",
  "body": "Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),\nBoer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:\n\nWe imaged the field of GRB 120909A detected by SWIFT\n(trigger 533060) with the TAROT robotic telescope (D=25cm)\nlocated at the European Southern Observatory,\nLa Silla observatory, Chile.\n\nThe observations started 40s after the GRB trigger\n(14s after the notice). The elevation of the field decreased\nfrom 54 degrees above horizon and weather conditions\nwere good.\n\nThe first image is trailed with a duration of 60.0s\n(see the description in Klotz et al., 2006, A&A 451, L39).\nWe detect the optical transient discovered by\nHaislip et al. (GCNC 13728).\n\nRelative photometric analysis is done using R=14.37\nfor the star NOMAD1 0305-0869420 (R.A.=275.7585731\nDecl=-59.4476147 J2000).\n\nThe careful analysis of the trail is compatible with a\nconstant magnitude of R=17.1 from T+40s to T+100s.\nThere is not optical peak during the gamma peak\nat T+48s reported by Ukwatta et al. (GCNC 13733).\n\nAfter the trailed image, a technical problem caused the\nlost of images until T+439s. Following images have been\nacquired using the classical diurnal drift.\n\nSummary of the first observations is:\n\nStart  Stop  Rmag  Error\n   40s  100s  17.1    0.1 (continuous photometry)\n  439s  529s  16.5    0.1\n  539s  629s  18.9    0.1\n  640s  729s  19.1    0.2\n  744s  834s  19.3    0.2\n  845s  935s  19.7    0.2\n\nMagnitudes are not corrected for galactic dust extinction\n(which should be about 0.4 magnitude in the R band according\nto D. Schlegel et al. 1998ApJ...500..525S).\n\nThis message may be cited.",
  "circularId": 13739,
  "createdOn": 1347268020000,
  "email": "Alain.Klotz@free.fr",
  "subject": "GRB 120909A: TAROT La Silla observatory optical observations",
  "submitter": "Alain Klotz at CESR-CNRS  <Alain.Klotz@free.fr>",
  "eventId": "GRB 120909A"
}