{
  "bibcode": "2013GCN.14248....1V",
  "body": "A.J. van der Horst (U. of Amsterdam), R.D.E. Saunders (MRAO),\nK.J.B. Grainge (U. of Manchester), R.P. Fender, T.D. Staley\n(U. of Southampton), A. Rowlinson, R.A.M.J. Wijers (U. of Amsterdam)\nreport on behalf of a large collaboration:\n\n\"We have observed the Swift/BAT error circle of GRB 130216A (GCN 14229)\nat multiple epochs with the AMI Large Array and the Westerbork Synthesis\nRadio Telescope, at 15 and 4.8 GHz respectively. The radio source we\nreported in GCN 14234 was clearly detected at all epochs at this\nposition: RA, Dec (J2000) = 04:31:34, +14:39:36 (+/- 2 arcsec).\nOur flux density measurements are given in the table below.\n\nEpoch              Delta T      Freq.     Flux density\n==============     ========     =======   ============\nFeb 16.94-16.98    0.03 days    15 GHz    0.78 +/- 0.08 mJy\nFeb 18.55-19.01    1.86 days    15 GHz    0.80 +/- 0.04 mJy\nFeb 19.51-19.59    2.62 days    4.8 GHz   1.11 +/- 0.09 mJy\nFeb 19.86-19.99    3.00 days    4.8 GHz   1.15 +/- 0.06 mJy\nFeb 20.50-20.64    3.64 days    4.8 GHz   0.92 +/- 0.07 mJy\nFeb 20.91-20.99    4.02 days    4.8 GHz   1.09 +/- 0.08 mJy\n\nThe source is constant in flux between our observing epochs and also\nwithin the 11-hour AMI observation. The spectral index between 4.8\nand 15 GHz is -0.3. There is no significant polarization detected\nin the combined Westerbork data, with a 3-sigma upper limit of 15%.\n\n From these observations we conclude that this source is not the\ncounterpart of GRB 130216A, but possibly a radio galaxy or AGN.\nBased on the combined 9C and 10C Surveys of Radio Sources\n(see, e.g., Davies et al. 2011, MNRAS, 415, 2708), we estimate that\nthe probability for a source as bright or brighter than the one we\ndetect to occur by chance inside the Swift/BAT error circle is 2%.\n\nWe would like to thank the AMI and WSRT staff for scheduling and\nobtaining these observations.\"",
  "circularId": 14248,
  "createdOn": 1361477701000,
  "email": "A.J.vanderHorst@uva.nl",
  "subject": "GRB 130216A: possible radio counterpart is steady field source",
  "submitter": "Alexander van der Horst at U of Amsterdam  <A.J.vanderHorst@uva.nl>",
  "eventId": "GRB 130216A"
}