{
  "bibcode": "1999GCN...491....1R",
  "body": "E. Rol, P.M. Vreeswijk (U. of Amsterdam), R. Strom (NFRA, U. of\nAmsterdam), C. Kouveliotou (USRA, NASA/MSFC), E. Pian (ITESRE,\nBologna), A. Castro-Tirado (LAEFF-INTA, Madrid), J. Hjorth (U. of\nCopenhagen) and J. Greiner (AIP, Potsdam) report on behalf of a larger\nEuropean collaboration:\n\n\"We have performed observations with the Westerbork Synthesis Radio\nTelescope (WSRT) at the position of the optical counterpart of\nGRB991216 (Uglesich et al., GCN 472), on Dec. 17 and 18 at 4.8 GHz and\n1.4 GHz, for 6 hours at each frequency.\nAt 4.8 GHz, we detect a 6 sigma radio source, coincident with the\nposition of the radio afterglow reported by Taylor et al. (GCN 483)\nand by Pooley (GCN 489). At 1.4 GHz, we do not detect anything at this\nposition, with an rms upper limit of 0.17 mJy. This upper limit can be\nreduced further.\n\nIf we split the observation into four epochs, we detect significant\nvariability of the flux intensity of the source at 4.8 GHz, as can be\nseen from the following table:\n\nUT Dec 1999\tflux (mJy)\tsigma (mJy)\n(mid obs.)\n17.783\t\t0.82\t\t0.13\n17.997\t\t0.84\t\t0.13\n18.044\t\t1.62\t\t0.13\n18.153\t\t0.70\t\t0.16\n\"\n\nThis message can be cited",
  "circularId": 491,
  "createdOn": 945539674000,
  "email": "evert@astro.uva.nl",
  "subject": "GRB991216 radio observations",
  "submitter": "Evert Rol at U.Amsterdam  <evert@astro.uva.nl>",
  "eventId": "GRB 991216"
}