{
  "body": "Lauren Rhodes (McGill), Andrew Hughes, Rob Fender (Oxford), Joe Bright (Oxford/Breakthrough Listen), Dave Green, Dave Titterington (Cambridge) report:\n\nWe observed the position of GRB 260310A/AT 2026fgk (Fermi GBM Team, GCN 43951; Konno et al., GCN 43974; Hinds et al., AstroNote 2026-65; O’Neill et al. 2026, TNS Discovery Report 294132) with the Arcminute Microkelvin Imager Large-Array (AMI-LA) at 15.2 GHz beginning at 2026 March 13 23:20:06 for a total of 8 hours. The flux standard 3c286 was used to calibrate the bandpass response and flux scale of the AMI-LA and J1435+7605 was used as an interleaved complex gain calibrator.\n\nWe detect an unresolved source with coordinates consistent with those of GRB 260310A/AT 2026fgk. We measure a peak flux density of 9.8 +/- 0.5 mJy/beam. Given the high flux density of the source, we cross checked with the VLASS survey and find no preexisting radio emission at the afterglow coordinates down to a 3sigma upper limit of around 0.5mJy/beam.\n\nWe thank the staff at the Mullard Radio Astronomy Observatory for carrying out these observations and operating the AMI-LA.",
  "circularId": 44005,
  "createdOn": 1773501836751,
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Lauren Rhodes at McGill <lauren.rhodes@mcgill.ca>",
  "eventId": "GRB 260310A",
  "version": 2,
  "format": "text/plain",
  "bibcode": "2026GCN.44005....1R",
  "subject": "GRB 260310A/AT2026fgk: radio detection at 15GHz",
  "editedOn": 1773516559027,
  "submittedHow": "web",
  "submitter": "Lauren Rhodes at McGill <lauren.rhodes@mcgill.ca>"
}