{
  "bibcode": "2023GCN.33697....1M",
  "circularId": 33697,
  "createdOn": 1682653839132,
  "subject": "GRB 230427A: GMG upper limit",
  "submitter": "Jirong Mao at Yunnan Obs <jirongmao@mail.ynao.ac.cn>",
  "body": "J. Mao, H.-C. Feng, and J.-M. Bai (YNAO) report:\n\nWe observed the field of GRB 230427A (Troja et al. GCN 33687) by the GMG telescope in Yunnan observatories.\nThe observation began from UT 14:52:28 April 27, 2023, about 4.3 hours from the trigger. We could not observe the optical\nafterglow down to a magnitude limit of R~20.6.",
  "eventId": "GRB 230427A"
}