{
  "bibcode": "2002GCN..1594....1M",
  "body": "K. Matsumoto (Okayama Univ.), T. Kawabata (BAO), K. Ayani (BAO), \nY.Urata (Titech / RIKEN), H. Yamaoka (Kyushu Univ.), \nN. Kawai (Titech / RIKEN) report:\n\n\"We have corrected our photometric data at Oct. 4 14:13 UT of the\nGRB021004 afterglow (reported in GCN1567), which was obtained by using\nthe R-band photometric reference USNO star RA=00:26:58.77,\nDEC=+18:56:56.1 as R=15.52 in the field photometry (Henden, GCN 1583),\nand present the additional preliminary results as follows.\n\nepoch  start time UT  exposure   R-mag.\n1      Oct. 4 13:57   60s        16.38\n2      Oct. 4 14:13   60s        16.36\n3      Oct. 4 14:55   60s        16.63\n4      Oct. 4 16:31   60s x 3    17.03\n\nTheir typical errors (1 sigma) are 0.12 mag.\n\nWe find that our point 1 is fainter than the magnitude extrapolated back\nfrom the observations at later epochs (decay index 1.32, Weidinger et al.\nGCN 1573).  This suggests that the break occurred during our\nobservations between 0.08 d and 0.2 d after the burst.\n\nAnalyses of the full data set of our time-resolved photometry in\nVRI-bands are underway.\"\n\nThis message may be cited.",
  "circularId": 1594,
  "createdOn": 1033981605000,
  "email": "urata@crab.riken.go.jp",
  "subject": "GRB021004: Update Bisei photometric data",
  "submitter": "Yuji Urata at RIKEN  <urata@crab.riken.go.jp>",
  "eventId": "GRB 021004"
}