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GCN Circular 212

Subject
GRB 990123 radio observations
Date
1999-01-24T19:19:16Z (25 years ago)
From
Titus Galama at U.Amsterdam <titus@astro.uva.nl>
T.J. Galama, P. Vreeswijk, E. Rol (U. of Amsterdam), R. Strom (NFRA
and U. of Amsterdam), J. van Paradijs (U. of Amsterdam and U. of
Alabama in Huntsville), C. Kouveliotou (USRA/MSFC), G. de Bruyn (NFRA
and U. of Groningen) report: 

"We observed the error box of GRB 990123 (GCN #199) at 4.88 GHz with
the Westerbork Synthesis Radio Telescope (WSRT) for 12 hours on
January 24.28 1999 UT. At the position of the optical transient (GCN
#201) we do not detect a radio source (< 130 microJansky; 3 sigma).
This result, when compared with the January 24.65 UT 8.46 GHz VLA
detection (260 +/- 32 microJansky; GCN #211) may be due to synchrotron
self-absorption, or otherwise, may indicate that the 4.88 GHz
observation was suppressed by interstellar scintillation.  Further
observations are planned."

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