Westerbork station report to TOG

VLBI Hardware

Mark 5 recorders
Westerbork bought two Mark5 recorder systems from Conduant. One has gone to JIVE and the other remained in Westerbork, and the Westerbork unit has now had a fibre gigabit ethernet card installed. The 2 recorders came with 2 empty disk packs and Harm-Jan Stiepel installed 8x180Gbyte IBM/Hitachi drives in each
Mk5 Disk packs and Disks
Westerbork bought 34 extra empty disk packs from Conduant, and 160 180Gbyte IBM/Hitachi disk drives to fill 20 of them (although only 19 have been assembled).
Terminator boards
We installed the terminators to the outputs on the Mark5a recorder
Dedicated eVLBI fibre
Westerbork has 2 distinct gigabit ethernet fibre connections to Dwingeloo since March 2004. One is a general purpose line for data communication and the other is a dedicated eVLBI connection between the Westerbork Mark5a terminal and one of the JIVE Mark5a units. The Westerbork side is connected to the (Alteon Networks Inc. AceNIC) gigabit ethernet card, and the onboard 100Mbit card is used for control and communication with the field system. The dedicated line is not switched so that the general traffic is not disturbed by eVLBI. Some eVLBI tests that used the general purpose line did disturb users in JIVE and ASTRON.
Disuse of Mark4 recorder.
During VLBI Session 2004-1 no tape recordings were done. Observations were all recorded via the Mark5a unit, although some eVLBI tests were done using it to route the data (via the general use line) to JIVE.
The Mark5a proved very reliable although some minor problems did occur.

Field System

Only minor changes were made to the field system. The system was updated to FS 9.6.9. A few alterations were made in the interfaces used by the single-dish VLBI setup to conform with local network and software changes.

System

5cm methanol receiver
The single 5cm reciever ( for methanol maser observations) was installed and tested after Session 2004-1. Local tests of sensitivity gave a telescope gain of 0.060 K/Jy and system temperature of 97K (SEFD=1600Jy). This is much closer to the 3.6cm system values than the 6cm system values.
This reciever gave fringes in the test observation F04M1 and local (autocorrelation) observations confirmed that we can observe maser lines.

Future

Fully digital tied array
I want to present an update on how that is progressing

Tony Foley (foley@astron.nl)
Last modified: Thu Mar 25 15:14:07 2004