TITLE:\tGCN GRB OBSERVATION REPORT\nNUMBER:\t40\nSUBJECT:\tGRB980329 VLA observations\nDATE:\t98/04/03 07:10:15 GMT\nFROM:\tGreg Taylor at NRAO\n\nG.B. Taylor, D.A. Frail (NRAO), S.R. Kulkarni (Caltech), and\nthe BeppoSAX GRB team report:\n\nWe have observed the field containing the proposed x-ray counterpart\n1SAX J0702.6+3850 of GRB 980329 (IAUC 6854) with the VLA at 8.4 GHz\non UT 1998 Mar 30.2, April 1.1, and April 2.1.  Observations on April\n1.1 detected a radio source VLA J0702+3850 within the 1 arcminute\nerror circle of 1SAX J0702.6+3850.  The coordinates of\nVLA J0702+3850 are: ra = 07h02m38.02170s dec = 38d50\'44.0170" (equinox\nJ2000) with an uncertainty of 0.05 arcsec in each coordinate.  The\nsize of this radio source is less than 0.25 arcsec.  The density of\nsources on the sky stronger than 250 microJy at this frequency is\n0.0145 arcmin**-2.\n\nThe flux density measurements of VLA J0702+3850 are as follows:\n\nDate(UT)   8.4 GHz Flux Density\n--------   ----------------------\nMar 30.2   166 +/- 50 microJy\nApr  1.1   248 +/- 16    "\nApr  2.1    65 +/- 25    "\n\nwhere the uncertainty in the measurement reflects the 1 sigma rms\nnoise in the image.  These measurements clearly demonstrate that\nthe radio source is variable on timescales of less than 1 day.\nThis rapid variability is similar to that observed in the\nradio afterglow from GRB 970508.  We propose VLA J0702+3850\nis the radio afterglow from GRB 980329.\n\nAdditional radio observations are in progress.\n
