Report to TOG meeting November 2004

VLBI hardware

• Westerbork recently bought enough 250Gbyte disks to fill all the empty packs we had (14). During the summer we had various problems with the air-conditioning and, when the backend system was overheated, one disk failed in the Mark5A.
• We have participated in several successful eVLBI tests using the dedicated eVLBI fiber connection to JIVE.
• The Mark4 tape unit was used during the October VLBI session and the brushless vacuum motor died one night during observations. Stiepel replaced it with a (old) reserve carbon-brush motor and got the system running again. However this motor does not switch vacuum levels so we can no longer record on thick tapes.

System

• We have used the (one) 5cm receiver in single dish mode during the November 2004 VLBI session. There were initial problems with a phase jitter in the LO system, but these were repaired and now it seems to perform well. Feedback from the results of the session is wanted.
• Westerbork now has an extension to the lower frequencies; it has a full array low frequency (100-180MHz) receivers which are designed to overlap with the highest frequencies of the LOFAR array. Although the interference levels are very high there are some narrow bands clean enough to make maps.

Field System

Developments

• The TADUmax project continues. The serial links needed to connect the digital outputs are now being produced.
• The air-conditioning will be replaced, so Westerbork will be out of service for a short time in January 2005. A new Faraday cage is at the moment being constructed to house many of the workstations to reduce self-induced RFI