TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3405
SUBJECT: GRB 050509B: WSRT Radio Observations
DATE:    05/05/10 14:50:54 GMT
FROM:    Alexander van der Horst at U of Amsterdam  <avdhorst@science.uva.nl>

A.J. van der Horst, K. Wiersema and R.A.M.J. Wijers (University of
Amsterdam) report on behalf of a larger collaboration:

"We observed the position of the GRB 050509B afterglow at 4.9 GHz with the
Westerbork Synthesis Radio Telescope at May 9 14.59 UT to May 10 2.59 UT,
i.e. 10.98 - 22.98 hours after the burst (GCN 3381). We do not detect a
radio source within the SWIFT/XRT error circle (GCN 3395), in particular
at the position of the four optical sources mentioned in GCN 3401.
The rms noise in het map within the SWIFT/XRT error circle is 22 microJy
per beam. The formal flux measurement for a point source at the center of
the SWIFT/XRT error circle is 3 +/- 22 microJy.
We detect a point source coincident with the position of the center of the
galaxy observed in the optical (GCN 3390), with a peak flux of 324 +/- 22
microJy."

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