TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  211
SUBJECT: GRB 990123, new radio source
DATE:    99/01/24 16:56:38 GMT
FROM:    Dale A. Frail at NRAO  <dfrail@nrao.edu>

D. A. Frail (NRAO), and S. R. Kulkarni (Caltech) report on behalf of a
larger NRAO/Caltech collaboration:

"We obtained a second VLA observation of the error box of GRB 990123
(GCN #199) beginning on January 24.65 UT at 8.46 GHz. At the location
of the optical transient (GCN #201) there is a new radio source with a
flux density of 260 +/- 32 microJy. A similar image taken on January
23.63 UT (GCN# 200) gives a 2-sigma upper limit at this same location
of 64 microJy. We are likely observing the slow "turn-on" of the
afterglow. Further observations are planned to track its expected rise
to maximum and its subsequent power-law decay."

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