{
  "bibcode": "2009GCN..9323....1R",
  "body": "V. Rumyantsev, E. Pavlenko, O. Antoniuk (CrAO), A. Pozanenko (IKI) report on \nbehalf of  larger GRB follow-up collaboration:\n\nWe observed the error box of  Swift GRB 090423 (Krimm et al. GCN 9198)  on \nApr. 23 between (UT)  090423 23:34:46 -- 090424 01:13:20 in R -filter with \nShajn telescope of CrAO.  The observation was planning and performed before \nthe redshift z ~ 8 of GRB 090423 was confirmed  (Cucchiara et al. GCN 9213; \nOlivares et al. GCN  9215; Thoene  et al.  GCN 9216; Tanvir et al.  GCN \n9219). Indeed we do not detect optical afterglow at the place of IR \nafterglow detection (Tanvir et al.  GCN 9202; Levan et al.  GCN 9206; \nCucchiara  et al.  GCN  9209).  Limiting magnitude of the combined image is \nfollowing :\n\nT0+     Filter, Exposure, mag.,     err.\n(d)                  (s)\n\n0.6877  R       93x60    >24.0 (3 sigma)\n\nThe combined R-image  can be found at \nhttp://grb.rssi.ru/GRB090423/GRB090423_ZTSh_a.gif",
  "circularId": 9323,
  "createdOn": 1241482898000,
  "email": "apozanen@iki.rssi.ru",
  "subject": "GRB 090423: optical limit",
  "submitter": "Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>",
  "eventId": "GRB 090423"
}