{
  "subject": "GRB 251222A: radio detection with the VLA",
  "submittedHow": "email",
  "createdOn": 1768490205158,
  "eventId": "GRB 251222A",
  "bibcode": "2026GCN.43415....1G",
  "circularId": 43415,
  "body": "S. Giarratana (INAF-OAB), M. Giroletti (INAF-IRA),\nG. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),\nN. Omodei (Stanford Univ.), O. S. Salafia (INAF-OAB),\nL. Nava (INAF-OAB)\n\nAt 03:47:54 UT on 2025 December 24 (T_mid = 1.48 days post-burst)\nthe Karl G. Jansky VLA observed the field of GRB 251222A /\nEP251222B (Fermi GBM team, GCN 43186, 43222; SVOM team,\nGCN 43188, GCN 43202; Einstein Probe team, GCN 43201, 43215;\nKonus-Wind team, GCN 43214; GECAM team, GCN 43218) in three\nbands, with central frequencies of 6, 10 and 15 GHz.\n\nThe standard 3C48 was used as bandpass and flux density\ncalibrator, while J0501-0159 was used as phase calibrator.\n\nFrom a preliminary analysis, an unresolved radio source\nis detected at a position (J2000):\n\nRA: 05:08:46.775 +- 0.001\nDec: -07:12:48.80 +- 0.02\n\nconsistent with the X-ray (SVOM team, GCN 43188, 43202; Einstein\nProbe team, GCN 43201, 43215; Swift/XRT team, GCN 43213) and optical\n(SVOM team, GCN 43189, 43203, 43208; An et al., GCN 43194; Calapai\net al., GCN 43195; Durbak et al., GCN 43197; Gupta et al., GCN 43207;\nGOTO collaboration, GCN 43209; Pérez-Fournon et al., GCN 43212;\nGupta et al., GCN 43224; Globus et al., GCN 43225; IKI-GRB-FuN team,\nGCN 43226, 43230, 43273; GRANDMA collaboration, GCN 43229, 43237;\nBusmann et al., GCN 43233; Lee et al., GCN 43236; Mephisto Team,\nGCN 43250) position of the transient.\n\nThe preliminary analysis yields the following results:\n\n================================================================\nT_mid\tFreq\tPeak\tr.m.s.\tBeam\t\tPA\n[days]\t[GHz]\t[uJy/b]\t[uJy/b]\t[arcsec^2]\t[deg]\n================================================================\n1.48\t6\t71\t7\t1.29x0.91\t-22\n1.48\t10\t208\t8\t0.75x0.58\t-16\n1.48\t15\t241\t8\t0.56x0.38\t-28\n================================================================\n\nNo source is detected with a >3sigma confidence level at the\naforementioned position in the VLASS. However, the r.m.s. noise\nlevel of the survey at the GRB location is approximately 150 uJy/b.\n\nWe would like to thank the staff of the VLA for approving, executing,\nand processing the observations.\n\nThe National Radio Astronomy Observatory is a facility of the National\nScience Foundation operated under cooperative agreement by Associated\nUniversities, Inc.\n\nThese observations were carried out as part of project SF181027,\napproved in the framework of the Fermi - NRAO joint program agreement.",
  "submitter": "Stefano Giarratana at INAF-OAB <s.giarratana@ira.inaf.it>"
}