[vsnet-grb-info 7960] GRB 090423: WSRT Radio Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9503
SUBJECT: GRB 090423: WSRT Radio Observations
DATE:    09/06/11 23:45:46 GMT
FROM:    Alexander van der Horst at NASA/MSFC  <Alexander.J.VanDerHorst at nasa.gov>

A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of a large
collaboration:

"We observed the position of the high redshift GRB 090423 afterglow
at 4.9 GHz with the Westerbork Synthesis Radio Telescope at May 22
11.47 UT to 23.46 UT, i.e. 29.15 - 29.65 days after the burst (GCN 9198).
We do not detect a radio source at the position of the infrared counterpart
(GCN 9202). The three-sigma rms noise in the map around that position is
75 microJy per beam. The formal flux measurement for a point source at the
position of the optical counterpart is 44 +/- 25 microJy.

We would like to thank the WSRT staff for scheduling and obtaining these
observations."