{
  "bibcode": "2007GCN..6434....1K",
  "body": "Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:\n\nWe imaged the field of GRB 070521 detected by SWIFT\n(trigger 279935) with the TAROT robotic telescope (D=25cm)\nlocated at the European Southern Observatory,\nLa Silla observatory, Chile.\n\nThe observations started 23.8s after the GRB trigger\n(8.5s after the notice). The elevation of the field decreased from\nfrom 24 degrees above horizon and weather conditions\nwere highly variable (cloudy).\n\nThe date of trigger : t0 = 2007-05-21T06:51:10.656\n\nThe first image is trailed with a duration of 60.0s\nfrom t0+23.8s to t0+83.8s\n(see the description in Klotz et al., 2006, A&A 451, L39).\nThe limiting magnitude is R ~ 17.1.\nWe do not detect any OT at the XRT position mentioned\nby Guidorzi et al. (GCNC 6431) but we have a faint\npatch at coordinates 16h10m37.5s (+/-0.5s) +30d14'58\"\n(+/-5\") J2000.0 near the limiting magnitude.\n\nThe second image is 30.0s exposure in tracking mode,\nno OT is detected:\nt0+89.4s to t0+119.4s : R > 17.5\n\nWe co-added a series of exposures:\nt0+89.4s to t0+570.3s : R > 19.0\n\nMagnitudes were estimated with the nearby USNO-B1 stars\nand are not corrected for galactic dust extinction.\n\nThis message may be cited.",
  "circularId": 6434,
  "createdOn": 1179733634000,
  "email": "Alain.Klotz@free.fr",
  "subject": "GRB 070521: TAROT La Silla observatory optical observations",
  "submitter": "Alain Klotz at CESR-CNRS  <Alain.Klotz@free.fr>",
  "eventId": "GRB 070521"
}