Westerbork Station Report Nov 2005 Since the lat CDB meeting Westerbork took part in 2 VLBI sessions (2005-2 and 2005-3) as well as several eVLBI tests. These sessions involved the use of both Mk4 tape and Mk5A disk recorders. Receivers There have been no major changes to VLBI receivers. Work has recently started to modify one receiver to provide a wider bandwidth (2x160MHz) at 3.6cm for geodetic observations. Recording Although the majority of observations are now done with Mark5A, there are still observations requesting the use of the Mark4 tape unit. The ceramic plate was flipped to its last available unused position (before session 2005-2) and vacuum motor on the Mark4 was replaced in October 2005 (shortly before session 2005-3). However, in October during a swap from Mark4 to Mark5A, a pin in one of the connectors from the formatter broke. This was quickly diagnosed and repaired, but this also demonstrates the fragility of these connectors when used with multiple disconnection-reconnection cycles. Westerbork also had problems with its Mark5A unit before session 2005-3, so we swapped it with a unit from JIVE. At present we still have the JIVE Mark5A in operation. We have now assembled disk packs with a total storage capacity of 87Tbyte - thus filling the requested capacity per station. The majority of these are in 2Tbyte packs. VLBI rack A new Field System computer was purchased from SWT (the recommended supplier). Although the documentation suggested that this PC had been tested, it was found that the documentation referred to another unit. However with some work locally the system was made to work and taken into production from August 2005. We also configured a wideband noise system (0-400MHz) so that it could be directly connected to the IF inputs of the VLBI rack. This was done to allow testing the recording systems and data paths for eVLBI without needing telescope time. Other System Changes The new Time and LO Distribution System was made operational shortly before session 2005-2. This supplies the 1pps and the 5MHz LO to the VLBI rack. This worked without major problems. During recent months workstations have been moved into the second Faraday cage, to reduce the sources of local RFI. The most recently moved (Nov 2005) is the telescope pointing computer, which communicates with the FS computer. The meteorological station will be replaced before the end of 2005, and this should improve the reliability of weather data used in tropospheric corrections, as well as more reliable local indication of storm conditions for stowing the telescopes. The prototype units for the fully digital tied array (TADU) are now under test. The TADU should be working sometime early in 2006. It is planned to connect this directly to the VSI-H interface of a Mark5B recorder, allowing us to decomission the (analog) VLBI rack during 2006. It may remain however for some single-dish geodetic observations with a wider-bandwidth IF input. Tony Foley