European VLBI Network - TOG Meeting, Jodrell Bank, 22 November 2004 Station Report for Jodrell Bank & Cambridge Telescopes Alastair Gunn Paul Burgess May 2004 Session This session comprised 10 experiments at C-band and 8 experiments at L-band. Since a wear fracture was beginning to become apparent on the Lovell telescope wheel girder, its use for phase referencing was restricted during this session. This meant that PIs were given the opportunity of switching to the Mk2 telescope instead. Hence, at C-band, 4 experiments used the Lovell telescope and 6 the Mk2 telescope. 4 experiments at C-band included Cambridge, one of which was also a joint MERLIN observation. At L-band, 3 experiments used the Lovell telescope and 5 the Mk2 telescope. Cambridge performed L-band observations for 3 experiments, none of which were joint MERLIN observations. The total allocated observing time was 241 hrs; 66 hrs on the Lovell, 123 hrs on the Mk2 and 52 hrs on Cambridge. Surprisingly, no time was lost due to weather or technical difficulties. Part of the reason for this success has been the reliability and ease-of-use of the Mk5 disk-based recording units. Only experiments to be correlated in Socorro were recorded on tape during this session, only 16% of data recorded. November 2004 Session This session comprised 12 experiments at P-band (90cm), 8 at C-band (6cm), 3 at K-band and 10 at C-band (5cm). Six of the 5cm experiments were joint EVN+MERLIN observations. P-band observations, totalling 97.5 hrs, were performed with the Lovell telescope. 6cm observations were also performed with the Lovell telescope for a total of 82 hrs. 48 hrs at K-band and 110 hrs at C-band (5cm) were observed with the Cambridge telescope. Originally, 48 hrs at K-band and 116 hrs at C-band (5cm) were allocated to the Mk2 telescope, but the telescope did not return from engineering work on the drive system in time for this session. K-band observations were cancelled, but for C-band (5cm) the MERLIN antenna at Darnhall was substituted for the Mk2. A total of 116 hrs were observed with Darnhall. Since the 5cm observations were mostly narrow-band (2MHz channels), the limited MERLIN microwave link bandwidth was not a constraint and PIs were thus provided with the requested data. In fact, since Darnhall was equipped with a new e-MERLIN C-band receiver, its sensitivity was much better than would have been achieved with the Mk2 telescope. The total allocated observing time was 501.5 hrs; 179.5 on the Lovell, 158 on Cambridge and 164 on Mk2/Darnhall. Most of the P-band observations were recorded on tape for correlation at Socorro; the remainder of the session was recorded on the Mk5 disk-based systems. During P-band observations, 3.9% of time was lost due to high winds and 4% due to minor equipment failures. For 6cm observations, 7.5% of time was lost to weather and 0.4 to equipment failure. For K-band, 100% was lost for the Mk2 (due to the ongoing engineering) and 0.3% for Cambridge due to equipment failure. For 5cm observations, no time was lost on Cambridge, although Darnhall lost 2.7% due to equipment failures, the most serious of which was vandalism on the telephone line at the outstation. The total lost time this session was 65.5 hrs (13%), or 17.5 hrs (3.5%) if the Mk2 downtime is not included. Technical Developments The second Mk5 unit is now fully integrated and operational. Both systems are now in regular use for both FTP and real-time VLBI testing, as well as user experiments. On 22nd September 2004 one of them was used with the Cambridge telescope for the EVN Science Demonstration. The VLBA tape deck will be decommissioned in 2005. We have purchased parts for, and assembled, a further 15 disk packs, making a total of 25 so far. We have funding for a further 10 to 15 packs, which we will defer whilst prices drop. Funding has been received for the VLBI-dedicated Gigabit fibre Internet link to JIVE. The fibre is installed and will be commissioned shortly. A student is working on bandwidth testing between Manchester and JIVE, and has found ~ 900Mbps to be feasible. Fibre NIC's have been ordered for the Mk5s. Over the summer our Field System PCs have been upgraded to FS Linux 5 (Debian), and the Field Systems are maintained at current release level. Our support hardware has been upgraded to handle large files and 1Gbit networking. Local control software has been upgraded, and the Darnhall dish is integrated into our system. It should be feasible to operate this telescope in addition to Cambridge by using spare capacity on the VLBA-rack Mk5 recorder. A fourth telescope may prove feasible. Clock and timing upgrades have been implemented. Status Table Updates -------------------- 1) New receivers available -------------------------- New Jb line in Table II - 90cm no longer available on Mk2 telescope |Jb-2 (d)| | | | 350=| 320=| | 320 | 910 | | 910 | | 2) Changes or new measurements of the SEFD ------------------------------------------ None. 90cm no longer available on Mk2 telescope 3) Changes in polarization characteristics ------------------------------------------ None. 4) Check and update if necessary the frequency range of each telescope at UHF band (30+ cm) (Footnote % in Table II) ------------------------------------------------------------------------- Not applicable. UHF no longer available at JBO. 5) Plans to built new receivers? -------------------------------- Yes. e-MERLIN receivers. C-band (5-6cm) now becoming available. Others later. 6) TABLE III: Frequency Agility ------------------------------- New Cm line in Table III - changes to PRC file required for band change |Cm | 180s | yes |18/21, 6, 1.3 |Changes in PRC file | 7) Table IIIA ------------- Correct. 8) Table IIIb ------------- New JB line in Table IIIb - new 5cm receivers will need changes to PRC file Current frequency range correct - may need changing after all new receivers are commissioned |Jb1/2| yes | yes | 6000-7000 | New 5cm RX in JB1 (2004) |