{
  "submitter": "Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>",
  "submittedHow": "email",
  "bibcode": "2025GCN.40049....1M",
  "body": "E. Mazaeva (IKI), E. Klunko (ISTP), N. Pankov (HSE), A. Pozanenko (IKI)\nreport on behalf of IKI GRB-FuN:\n\nWe observed GRB 250402A (Chen et al. GCN 40014) with the AZT-33IK telescope\nstarting on 2025-04-03 (UT) 18:11:28. We found the optical counterpart (Xin\net al., GCN 40015; Pérez-Fournon et al., GCN 40020; Schneider et al., GCN\n40022; Magnani et al., GCN 40023) at the position reported by Xin et al.,\nGCN 40015.\n\nPreliminary photometry of the optical counterpart is the following\n\nDate UT start t-T0 Filter Exp. OT Err. UL(3sigma)\n(mid, days) (s)\n\n2025-04-03 18:11:28 0.81567 R 29*120 21.9 0.2 22.3\n\nThe photometry is based on the nearby PS1 stars (R mag by Lupton\ntransformations).\n",
  "circularId": 40049,
  "subject": "GRB 250402A: Mondy optical observations",
  "createdOn": 1743776646471,
  "eventId": "GRB 250402A"
}