{
  "bibcode": "2002GCN..1363....1K",
  "body": "T. Kato (Kyoto U.), H. Yamaoka (Kyushu U.), R. Ishioka, M. Uemura\n(Kyoto U.) report on behalf of the VSNET GRB team:\n\n   We observed GRB 020331 (=H1963, the \"Easter\" burst detected by HETE,\nGCN 1315) using unfiltered ST-7E CCD cameras on 25-cm and 30-cm telescopes\nlocated at Kyoto University.\n\n   The initial exposure started at 17h 19m 42s (7 min after the burst\nlocalization, 47 min after the burst detection).  PSF photometry of\nmeasurable 24 images yielded 2.0-sigma detection at the reported\nafterglow (GCN 1339).  The object was found to be 6.4 mag (on 31.734 UT,\naverage of exposures) fainter than GSC 6166.129.  After a link with field\nphotometry by Henden (GCN 1319), we obtained a magnitude of 17.9 (system\nclose to Rc), with 1-sigma limits of 17.5-18.7.  The magnitude seems to be\nmarginally brighter than the extrapolation with the reported power index\n(GCN 1346).\n\n   The observation not only makes the earliest positive detection of\na GRB afterglow detected by HETE, but also makes the first evidence\nthat a GRB optical afterglow within ~1 hour of the burst can be at least\nas bright as expected from the later power-law decay.\n\nThis message may be cited.",
  "circularId": 1363,
  "createdOn": 1018600408000,
  "email": "tkato@kusastro.kyoto-u.ac.jp",
  "subject": "GRB 020331 Kyoto observation on March 31",
  "submitter": "Taichi Kato at Kyoto U  <tkato@kusastro.kyoto-u.ac.jp>",
  "eventId": "GRB 020331"
}