{
  "subject": "GRB 240821A: GMG Optical Upper Limit",
  "createdOn": 1724395793913,
  "submitter": "Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>",
  "bibcode": "2024GCN.37242....1L",
  "body": "R.-Z. Li, B.-T. Wang, F.-F. Song, J. Mao, K.-X. Lu and J.-M. Bai (YNAO, CAS) report:\n\nWe observed the field of GRB 240821A, reported by Fermi/GBM (GCN 37219, GCN 37239), SVOM/ECLAIRs (GCN 37220, T0 at 2024-08-21T18:35:50.150), GRANDMA/LesMakes-T60 (GCN 37225), SVOM/GRM (GCN 37226), EP/FXT (GCN 37230) and Swift ToO (GCN 37236), using the GMG-2.4m telescope at Lijiang Observatory.\n\nThe observation began at 2024-08-22T16:10:10, about 21.57 hours after the SVOM/ECLAIRs trigger. \n\nNo new reliable optical counterpart was detected in the 2x600s stacked image within the 10-arcsec EP/FXT error circle of the afterglow candidate EP J233704.9-101126 (Turpin et al., GCN 37230), down to a 5-sigma limiting magnitude of R ～ 19.6, derived from calibration against the USNO-A2.0 field stars.\n\nThe detection limit was relatively shallow because of the lunar phase and the angular distance between the target and the Moon.\n",
  "circularId": 37242,
  "eventId": "GRB 240821A",
  "submittedHow": "email"
}