TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  152
SUBJECT: GRB980703 Very Long Baseline Interferometry
DATE:    98/08/27 15:49:28 GMT
FROM:    Greg Taylor at NRAO  <gtaylor@aoc.nrao.edu>

GRB 980703 Very Long Baseline Interferometry Observations

G. B. Taylor, D. A. Frail, A. J. Beasley (NRAO) and S. R. Kulkarni
(CIT) report:

Using the Very Long Baseline Array (VLBA) we have detected the radio
source identified as the afterglow from GRB 980703 (GCN #128).  During a
5 hour VLBA run on 1998 Aug 2 the radio source was found to have a
flux density of 580 +/- 60 microJy at 8.4 GHz.  The source is
unresolved by these observations with a size less then 0.3 mas (size <
2 pc given the redshift of 0.9660 reported by Djorgovski et al. in GCN
#139).  The position of GRB 980703 is R.A.=23h59m06.6661s,
Dec.=+08d35'07.09390" (equinox J2000) with an uncertainty of
approximately +/-0.0005" in each coordinate.  This measurement is
consistent with that given by Frail et al. (GCN #141) with errors of
+/- 0.05".

Given the accuracy of the VLBA position for the afterglow (0.5 mas = 4
pc), it would be of interest to register the afterglow on subarcsecond
resolution observations of the host galaxy.  Accurate absolute
astrometry at other wavebands are encouraged.

This report can be cited.