{
  "bibcode": "2018GCN.22977....1S",
  "body": "M. Sasada, T. Nakaoka, M. Kawabata, N. Uchida, Y. Yamazaki,\nK. S. Kawabata (Hiroshima Univ.) report on behalf of Kanata team:\n\nWe performed optical and NIR imaging polarimetry to the field of the\nGRB 180720B (Siegel et al. GCN 22973; Martone et al. GCN 22976) from\n2018-07-20 14:22:57 UT (73 seconds after the trigger) with HOWPol \nand HONIR attached to the 1.5-m Kanata telescope at Higashi-Hiroshima\nObservatory, Japan. We detected a bright optical counterpart of the \nGRB within the the Swift-XRT error circle of the X-ray afterglow. The\nmagnitude of the optical counterpart was R~9.4 mag in our first frame \ntaken with 30 second exposure and then smoothly declined. Further\nanalysis is ongoing.",
  "circularId": 22977,
  "createdOn": 1532103668000,
  "email": "kawabtkj@hiroshima-u.ac.jp",
  "subject": "GRB 180720B: Kanata 1.5m optical/NIR observation",
  "submitter": "Koji Kawabata at HASC,Hiroshima U  <kawabtkj@hiroshima-u.ac.jp>",
  "eventId": "GRB 180720B"
}