Effelsberg Water-Vapour Radiometer  -  REPORT TO THE TOG  -  30 JUNE 2003
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An 18 to 26 GHz scanning water-vapour radiometer was installed at
Effelsberg in March 2003 for atmospheric phase and opacity correction
of high-frequency VLBI experiments.  It observed in parallel with the
1.3 cm EVN session in June 2003 and during the 3 mm VLBI session in
April 2003.  The data are in Bonn awaiting validation by comparing
to the VLBI data when correlation is complete.

After validation, we need to clear a path for the radiometer data
streams to be archived and to use the corrections in the EVN
calibration pipeline routinely.

Stations that observe the higher EVN frequencies could improve their
sensitivity and calibration accuracy if they use water vapour
radiometers.  Radiometers operate now at Onsala, Effelsberg and
Wettzell, and outside the EVN at Pico Veleta, Plateau de Bure, TIGO,
Haystack, Hat Creek, Owens Valley, and Goldstone.

A.Roy