{
  "bibcode": "2003GCN..2129....1T",
  "body": "G. B. Taylor (NRAO), E. Berger (Caltech), D. A. Frail (NRAO), and\nS. R. Kulkarni (Caltech) report:\n\n\"Following the detection of the radio afterglow on Mar 30 (Berger\net al. GCN 2014) from the bright burst GRB 030329 (GCN 1985, 1997)\nwe observed with the Very Long Baseline Array (VLBA) for\n8 hours beginning on April 01.05 UT.  The flux density measured at\n8.4 GHz was 8.3 +/- 0.4 mJy.  The source is unresolved by these\nobservations with a size less than 0.5 mas (size < 1.4 pc given the\nredshift of 0.1685 reported by Greiner et al. in GCN 2020).\nAssuming typical parameters for the expansion (e.g. Frail et al. 2000, \nApJ, 534, 559) we expect a size of about 1.3e17 cm\n(0.04 pc) at the time of the VLBA observation (t=2.7 days).\nThe VLBA position is at ra = 10h44m49.9595s dec = +21d31'17.438\"\n(equinox J2000) with a conservative error of 0.001 arcsec in each\ncoordinate.  This position is within 0.02 arcsec of the VLA radio position,\nbut is 1.21 arcsec from the optical afterglow position\nreported by Yamaoka et al. (GCN 1994) who claim an uncertainty of 0.07\narcsec.  Given that the optical and radio afterglow should be\ncoincident, we suggest that the optical astrometric position \nsuffers from a systematic error.\n\nHigh frequency VLBI observations are planned with the goal of \neventually resolving the radio afterglow.\"\n\nThis message may be cited.",
  "circularId": 2129,
  "createdOn": 1049945558000,
  "email": "gtaylor@aoc.nrao.edu",
  "subject": "GRB 030329 VLBA Observations",
  "submitter": "Greg Taylor at NRAO  <gtaylor@aoc.nrao.edu>",
  "eventId": "GRB 030329"
}