Parkes Observatory report

Staff

Two new staff members have just joined us to bring the Parkes team back up to full strength in cryogenics and receiver support. Brett Dawson joined us from Ericsson in December as our new receiver engineer.

David Catlin started in January as our receiver technician, and at the start of the second week rushed back to Sydney for the birth of his second child. Mother Tracey and new daughter Emily are both well, and together with their three-year-old Bryn should be moving to Parkes to join Dave in a few weeks. Dave has moved to the ATNF from a position with a contractor maintaining flight simulators for the RAAF at Richmond.

Our administrative trainee, Louise Munday, left towards the end of the year. Lou made a major career advancement to the position of Assistant to Peter O'Keefe, head of People Development at CSIRO Corporate in Canberra. Lou has been tireless in her role as Observatory `front-person' over the last year and her cheerful presence will certainly be missed.

A new administrative trainee, Bonnie Lanzarini, has just joined us. Bonnie will be in the front office answering the phones on Tuesdays and Wednesdays and will be completing her TAFE studies on other days of the week. Until recently Bonnie was living near Venice, so adds multilingual virtuosity to her other many skills.

Sincere thanks are due to Noel Freeman who stepped in at short notice to provide essential administrative support over December when both Geoff Freeman and Julia Hockings were away for a few weeks. Noel's calm intelligence, capability and unflappable nature made a busy period managable. We wish him well as he starts his studies at Charles Sturt University in Bathurst.

Coffee and foccaccia and other goodies

Construction of the cafe in the grounds of the Parkes Visitors Centre is well underway. In one week prior to Christmas the site was transformed from bare dirt to one bearing a dramatic steel structure - the frame of the cafe and new covered BBQ area. The accompanying photo shows the cafe as it was when the builders took a break for Christmas. Assuming all continues according to plan, the cafe will be open for operation around the end of March - just in time for the Easter rush.

Figure 1: Café at Parkes Observatory around Christmas 2002

CPSR2

The new Caltech-Parkes-Swinburne baseband recorder continues to be honed into a fully commissioned machine. The only important remaining step is to repackage the equipment into two, large fully-shielded racks, whose manufacture to specifications has taken longer than expected.

Surface upgrade

The upgrade of the telescope surface - as part of the preparations for Mars tracking in late 2003 - early 2004 - is about to start. Around 180 new perforated aluminium panels will be fitted to the telescope in March, replacing half of the remaining steel mesh panels. Six of the new panels have just been fitted - a major effort in more than 40 degree heat accompanied by strong winds, smoke and dust on one of the most unpleasant days in Parkes so far this summer. Despite the elements the fitting was completely straightforward and the panels look great. The remaining 174 will be fitted over a period of four weeks, followed by a week or so of holography and adjustment of the surface.

Initial holography measurements at 12 GHz using beacons on the Optus satellites are in progress at the time of writing and will set a good baseline from which start the final adjustment of the panels in March - April.

Together with a new 8-GHz receiver being built by the Marsfield receiver group, the upgrade will result in a doubling of the sensitivity of the telescope at 8.4 GHz, and the extended aluminium surface may facilitate further receiver developments between 6 - 25 GHz in future years.

10/50cm Pulsar receiver

Fitting tests of the eagerly awaited 10/50-cm receiver took place on 28 January and went so well that the receiver was installed and removed from the focus cabin in around 9 hours - much less than the 24 hours set aside for the job. The receiver is so large that it will need to be installed (and removed) in two parts - but Pat Sykes and Graham Moorey have come up with an elegant system for aligning the two halves which worked beautifully. The current plan is for the installation of a fully functional receiver to take place in August, before Mars tracking begins in earnest.

Operations news

Impressions of the current El Nino climate cycle have been that it has been drier (of course) and hotter and windier than usual this year. The last several months have been extraordinarily windy, with more than 10% of time lost this year to date due to wind. Time lost to equipment faults is small by comparison.

The new zenith drive gears fitted to the telescope in October last year continue to work well with no major problems. The final stages of the work in October involved the grinding of each tooth on the zenith rack gears attached to the counterweight. The grinding was done using air-operated but hand-held grinders, working 12 hours a day over a period spanning a week and a half. This mammoth job was completed with unfailing cheerfulness by Chris Titterton and Daniel Jukic from Hofman's - a Perth based gear company - together with Clive Murphy from Narrabri. The results are a very obvious improvement in the shape of the teeth and the contact pattern between them and the teeth of the output pinions, reducing wear.

A number of niggling faults in the drive system have arisen in the last few months. While the drives have exercised the problem-solving skills of the local technical staff - which are considerable - little observing time has been lost.

Notable was a temporary apparent increase in friction in the zenith drive system which had the effect of reducing the motor currents when near the dish horizon. This may well reflect the much better meshing of the gears and the rack resulting from the gearbox and rack refurbishment last October. Attempts to characterize the friction have led to the identification (and correction) of a manufacturing fault in the drive control-electronics. The most recent tests indicate that the frictional losses have now decreased to almost the same level as recorded in the old zenith gearboxes back in April 2000, presumably as a result of the `bedding in' of the new gears and bearings. Some aspects of this issue are not yet fully understood and we will continue our tests and monitoring.

Subtle earth fault problems have also provided challenges. One led to power for the azimuth brake solenoids leaking across to the zenith brake solenoids with potentially serious consequences. Another resulted in the significant differential ground potential between different buildings on site corrupting the timing signals on the station clock.

Operational developments

At the time of writing, the first astronomical observations using the wideband correlator are underway. The new correlator provides up to 1 GHz of bandwidth, dual polarization, for pulsar timing and also for spectral-line work. In addition to increased sensitivity, the correlator provides full polarization capability, filling the vacuum in this area left by the demise of the Caltech correlator a year or more ago.

At present the correlator is being used at 256-MHz bandwidth with the multibeam correlator, through the standard conversion rack, and is producing high-quality data, with only relatively minor software wrinkles left to be smoothed out. Both the new correlator and CPSR2 have been successfully integrated into TCS (Telescope Control System), the Observatory's main observing interface.

Bringing the correlator into full operation is the culmination of many months of hard work, most significantly from Warwick Wilson and Evan Davis, the architects of the system. Mike Kesteven, Mark Calabretta and Simon Hoyle have all made important contributions to the software, as has Aidan Hotan from Swinburne.

John Reynolds
Parkes Officer-in-Charge
(John.Reynolds@csiro.au)