{
  "bibcode": "2009GCN..9063....1K",
  "body": "D. A. Kann, U. Laux, F. Ludwig and B. Stecklum (TLS Tautenburg) report:\n\nWe observed the afterglow (Updike et al., GCN 9026, Cenko et al. GCN 9027) \nof the intense Fermi GBM/LAT GRB 090323 (Ohno et al., GCN 9021) with the \n1.34m Schmidt telescope of the TLS Tautenburg observatory at several \nepochs.\n\nAt ~6 days after the GRB, conditions were bad (low transparency and \npassing clouds). We obtained 21 Rc frames of 600 seconds exposure time \neach. Only four of these are usable. The afterglow is faintly detected in \nthe complete stack.\n\nUsing the same comparison star as Kann et al. (GCN 9033), we measure the \nfollowing afterglow magnitude:\n\ndays after trigger\tExposure\tRc\tdRc (statistical)\n\n5.89127\t\t\t4 x 600\t\t23.13\t0.50\n\nAt ~7 days after the GRB, conditions were very bad (almost complete \novercast). We obtained 1 Rc frames of 600 seconds exposure time which had \ngood quality. The afterglow is not detected.\n\ndays after trigger\tExposure\tRc\n\n6.99881\t\t\t1 x 600\t\t> 22.50\n\nThis limit is not constraining.\n\nAt ~9 days after the GRB, conditions were very good (good transparency, \ngood seeing, but influence of moonlight). We obtained 12 Rc frames of 600 \nseconds exposure time each. The afterglow is faintly detected in the \ncomplete stack.\n\ndays after trigger\tExposure\tRc\tdRc (statistical)\n\n8.90324\t\t\t12 x 600\t23.64\t0.36\n\nCompared to the flattening of the decay noted by de Ugarte Postigo et al. \n(GCN 9051) and already hinted at in earlier TLS and Lick data (Kann et \nal., GCN 9041, Perley, GCN 9042), the decay has steepened again, an \nindication of a (jet?) break. On the other hand, the last TLS detection \nagrees well with the extrapolation of the earlier decay (Kann et al., GCN \n9041), indicating that the plateau may be a rebrightening/optical flare \nspanning a few days.\n\nDue to increasing moonlight, no further TLS observations are planned.\n\nThis message may be cited.",
  "circularId": 9063,
  "createdOn": 1238552566000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 090323: Further TLS detections - a break?",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 090323"
}