TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3177
SUBJECT: GRB050401, radio observation at 4.8 GHz and 8.64 GHz
DATE:    05/04/04 12:21:42 GMT
FROM:    Kinwah Wu at MSSL-UCL  <kw@mssl.ucl.ac.uk>

L. Saripalli (ATNF, CSIRO), K. Wu (MSSL, UCL), K. K. Ghosh (NASA-NSSTC),
D. A. Swartz (NASA-NSSTC) and A. F. Tennant (NASA-MSFC) report of radio
observations of GRB050401.

We observed the field of the GRB050401 using ATCA (6 km configuration)
at Narrarbri, Australia on 2005 April 02 15.02 UT and April 03 14.22 UT.
The duration of each observation was 1 hour.

We do not detect signals above rms of 0.5 (4.8 GHz) and 0.6 mJy (8.64 GHz)
in the field in each individual data set for the two observations. We also
do not find significant signal above an rms of 0.4 mJy for the combined
data set at 8.64 GHz. There appears to be a 2.5-sigma feature (rms of
0.3 mJy) at the position of the source (ref GCN 3163) in the combined 
data set at 4.8 GHz. The feature could be spurious given that the uv
coverage was poor and the observation duration was short.

The observations were granted as ToO (April 02) and discretion observation
(April 03) by the ATNF director.