{
  "circularId": 37533,
  "subject": "GRB 240821A: radio observation with the VLA",
  "submitter": "Stefano Giarratana at INAF-OAB <s.giarratana@ira.inaf.it>",
  "bibcode": "2024GCN.37533....1G",
  "eventId": "GRB 240821A",
  "createdOn": 1726585952768,
  "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)\n\nAt 04:07:30 UT on 2024 September 6 (T_mid = 15.43 days post-burst)\nthe Karl G. Jansky VLA observed the field of GRB 240821A\n(Fermi GBM team, GCN 37219; SVOM team, GCN 37220, 37226) at a\ncentral frequency of 6, 10 and 15 GHz.\n\nThe standard 3C48 was used as bandpass and flux density\ncalibrator, while J2358-1020 was used as phase calibrator.\n\nFrom a preliminary analysis, we do not detect the radio counterpart\nof GRB 240821A. During the observation, the VLA site was hit by a\nthunderstorm, which heavily affected the success of the experiment.\nWe derive the following upper limits (UL; 3sigma):\n\n==================================================\nT_mid   Freq  UL     r.m.s.   Beam        PA\n[days]  [GHz] [uJy]  [uJy/b]  [arcsec]    [deg]\n==================================================\n15.43   6     51     17       1.75x0.93   -38\n15.43   10    54     18       0.95x0.62   -29\n15.43   15    130    43       0.87x0.38   -44\n==================================================\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 SF171028,\napproved in the framework of the Fermi - NRAO joint program agreement.\n",
  "submittedHow": "email"
}