Compact Array and Mopra report
Staff and visitors
In late 2002, we farewelled Judy Stump and welcomed back Jacqui Wieringa. Judy served as the observatory's librarian while Jacqui was on maternity leave. Also in late 2002, we farewelled Steven Tingay, who has left to take up a position at Swinburne. Steven had been with us for three years as a Bolton postdoc, working mainly on radio galaxies and VLBI observations. With his new role in the Swinburne SKA group, and with his continuing interest in using the Long Baseline Array, we expect that Steven will be a frequent visitor to the ATNF sites. In mid-January we welcomed Michael Dahlem. Michael will be working on various systems-related projects at the observatory, including work related to the two MNRF programs, the SKA and tracking the radio-frequency interference environment at Narrabri.
The last few months have been a hive of activity with medium to long-term stays by five undergraduate students. Kate Smith (University of Albuquerque) left us in November after staying at Narrabri for three months, and learning the madness of Melbourne Cup on her final day. Kate worked on understanding high frequency source counts for CMB experiments. Andrew Danson (University of Newcastle) and Suzie Molloy (Monash) have been with us since early December as part of the ATNF Vacation Scholarship Program. Suzie has been busy using genetic algorithms to predict atmospheric phase given measurements from our two water-vapour radiometers. In early January, Le Cuong Nguyen (UTS) joined us to do six months of industrial experience as part of his computer science degree. Le Cuong and Andrew are developing new components of the ATCA monitoring system, as well as helping with some computer systems administration. In mid-December, Prue Sutton (University of Newcastle) started two months of work, studiously copying to disk and crosschecking the ATCA data archive (see below).
Archive to disk project
In conjunction with Rob Power at CSIRO Mathematical & Information Science (CMIS), over the Christmas period the entire Compact Array data archive has been copied from CDs onto a disk farm. All 1.5 Terabytes of the archive now sits on CMIS disks in Canberra (it is also backed up onto 53 DLT tapes). This is an early step in the process of developing the Compact Array archive as an example of a "virtual observatory". It also provides a duplicate copy of the archive in a physically distinct place to Narrabri. Our next step in the coming few months is to make the disk archive accessible over the Internet, and thus streamline the data archive request process. In the longer term, various grants are funding a collaborative project between the ATNF and CMIS to develop an ATNF virtual observatory focused on the ATCA archive.
Operations
The lost time was somewhat higher than normal. Lost time can be broken into three roughly equal components. Firstly, the term has been unusually windy: a third of the lost time was a result of wind-stow conditions. Secondly, as luck would have it, a nearby lightning strike during a severe thunderstorm on Christmas evening caused damage in numerous array systems. Rather than a relaxing Boxing Day, several staff were out at the Array attending to the problems. Considering the amount of damage, it is a tribute to them that four antennas were back up in the mid-afternoon, and that normal observing was restored by lunch on 27 December. The same lightning strike knocked out the University of Birmingham dome and IPS for considerably longer than this. The remaining third of downtime consisted of numerous smaller faults. The (old) antenna control computers remain our single-biggest "non-weather" source of lost time. 
Figure 1: ATCA usage for September 2002 term
User feedback
Figures 2 and 3 summarize the results from the Narrabri user feedback questionnaires in 2002. Figure 2 is for all observers, whereas Figure 3 shows the results of questions specifically related to the new 3- and 12-mm systems. Users rate various aspects of the observatory on a scale of 1 (poor) to 5 (excellent). 
Figure 2: User feedback for 2002
Figure 3: Millimetre systems user feedback for 2002
Upgrading the Compact Array
With the coming of summer, observing at 3- and 12-mm wavelengths finished for the year on 21 October and 7 November respectively. Although there were two 12-mm runs in early January, millimetre observing does not start fully until the second-half of April. With the first winter of "common user" observing with the interim millimetre receivers complete, we can now start to make more meaningful estimates of the fraction of time useful for millimetre observing. An analysis of weather patterns indicates that during winter months, a simple swap scheduling scheme would increase the chances of getting good weather from 65% to around 80 - 90%. For further information see www.atnf.csiro.au/observers/docs/3mm/weather/2002.html
The upgrade of the antenna control computers (ACCs) is tantalisingly close to completion at the Compact Array. Observing with the new ACCs is now routine, and we have successfully used the new ACCs during the calibration observations needed immediately after a re-configuration. In general we now expect observations in unallocated time to use the new ACCs. Some frustrating `pSOS' bugs are currently preventing a straightforward remote reboot of the new ACCs. We believe the ability to do this is critical before we switch to using these fully.
Regarding the millimetre receiver upgrades, a shutdown is scheduled for 1 - 10 April to outfit the Array with 12-mm receiver packages on the remaining three antennas. A second shutdown in May will complete the 12-mm upgrade. After May, module swaps will no longer be required, and the full 16 - 25 GHz band at 12 mm will be available. Between the April and May shutdowns, much of the 12-mm system functionality will be available, but there will be some practical restrictions on its use because of some missing components. Unfortunately the 3-mm upgrade has not proceeded as quickly as expected. The local-oscillator system for the 3-mm receivers is missing some critical components. This means that, at best, only one additional 3-mm system will be delivered this year, probably late in the winter.
A new round of holographic measurements were made on antenna CA02 in December. Apart from the innermost ring (which is approximately 0.8 mm offset from its nominal position) the panel alignment has an rms of 200 microns. The results are in broad agreement with photogrammetry done on this antenna in February 2002.
The work on the deformation on the main antenna structure with elevation (page 16) has led to a project to provide better sub-reflector control: the sub-reflector will be given both axial and a tilt control. Using these, we hope to improve the primary beam shape and to recover some lost antenna gain at lower elevations.
Visitors Centre and special events
The Visitors Centre had approximately 11,000 visitors in 2002 and several after-hours star evenings, such as for the Vintage Car Club. Plans are currently being drawn up to renovate the surrounding gardens, including an exploratory pathway and a spiral galaxy inspired area.
In November the observatory hosted a meeting by the CSIRO Business Development and Commercialisation unit (BD&C, Figure 4), with an unusual twist as the participants were unaware of their destination until the flight departed!
Figure 4: Mehrdad Baghai, Director BD&C, presenting a memento to Prof Ron Ekers
Mopra
Observing at Mopra using the 3-mm SIS system continued until 10 November 2002. Over the summer period, Mopra has been used as a VLBI-only telescope. Mopra continues to support both the once-a-term VLBI observing week and approximately weekly observations in conjunction with the VSOP mission. Figure 5 gives the number of 24-hour days of scheduled observing at Mopra in 2002. Overall, usage was very similar to 2001, with a total scheduled observing time of 142 x 24 hours.
Figure 5: Mopra time use in 2002
On 27 October, as part of the Coonabarabran "Festival of the Stars", we held a Mopra Open Day. In total we had about 110 visitors come through the observatory, look through the Control Room and climb up to the Vertex Room.
Bob Sault
Officer-in-Charge, Narrabri
(Bob.Sault@csiro.au)