Australia Telescope Compact Array report
Staff
Ben Reddall has taken a one year position at the South Pole providing engineering support for the DASI CMB telescope. Martin Oestreich has moved from Sydney to take on the role of Electronics Group Leader.
The Observatory welcomes new staff members who have joined the team.
David Brodrick joined the Computer Group in late December and has started work on the ATOMS/ACC project. He is also relieving John Giovannis from his system administrator duties for one day a week;
Rudi Behrendt was appointed as Technician in the Electronics Group to work with Shaun James in the power / drives / communications area. Also appointed to the Electronics Group is Cliff Harvey as Technical Assistant, who is working with Alan Day in the Cryogenics Lab;
Anni Reynolds is now with the Administration Group and is filling in the role of Administration Officer for Kylee Forbes while on maternity leave. Congratulations to Kylee and Simon on the birth of baby boy Jake. Margaret McFee will be with us for a period working as Administration Assistant / Receptionist. Thanks to Dianne Harris who departed the Observatory prior to Christmas after working in Administration / Reception for several months.
We farewell Leigh Panton who left in early February for a new job on the Gold Coast utilising skills in fibre optics work gained during many months of working on the Array in the "splicing caravan". We wish Leigh all the best in her new endeavours.
From February 2001 Dave McConnell will be working from the Sydney office for approximately one year. Dave will retain the official role as OIC, undertaking management functions and TAC scheduling and will return to Narrabri on a monthly basis for a week at a time. Dave will also be making major inputs to the ATOMS/ACC project while in Sydney. Ron Beresford, who has recently taken on the role as Deputy OIC, will be managing the day to day operations of the Observatory.
Operations
Compact Array Usage
The chart below (Figure 1) outlines details of Compact Array usage for the 2000 October observing period (2000OCTT). The final term of the year usually extends for four months from September. In 2000 the observing periods were adjusted to account for the Sydney Olympic games and possible difficulties in purchasing air tickets to Australia during this time. The fraction of time spent in maintenance was higher than usual because of the two week MNRF installation period in November and December, and the shorter than usual term. The large "unallocated" period arose partly from the difficulty in scheduling the Christmas/New Year period.
Figure 1: Compact Array Usage for 2000OCTT
User Feedback
The table below is compiled from observer assessments of the quality of support at the Observatory, with 5 being the highest score. The table compares figures for the years 1996-1999 and the three individual observing terms for 2000.
Table 1 - ATCA User Feedback
New Correlator interface
The VMS machine ATRIA, which has controlled the Compact Array correlator for a number of years, has been replaced by a new machine and software running under Linux. The users' interface to the correlator (still on a screen on the control room desk) has a more modern look _ it is graphical! One of the great new features is the ability to view spectra from all baselines and polarisation products simultaneously. This is a wonderful thing, allowing rapid assessment of the system health, strength of interfering signals, etc.
Compact Array Upgrade
The highlight of the recent period was the first use of two receivers operating at 3.5-mm wavelength. This exciting event and some early results from the first Southern Hemisphere mm-wave interferometer are described elsewhere in this newsletter. Other activities in the upgrade program are mentioned here.
ATOMS/ACC
The project now has a good workforce with Scott Cunningham, David Brodrick, Dave McConnell and Mark Wieringa making contributions. Dave McConnell is making progress on the monitoring front (VMON): we can now successfully retrieve multiple monitor points using java and the pSOS ds driver, and get the data back onto the VMS machines. Scott is working on the CYCLE component, getting into the details of the event setups and environments. The problems with PCI bridges have been overcome with a new motherboard that provides 4 primary PCI slots. David Brodrick has tracked down and fixed a problem with the encoder interface. He is currently working on software to drive the new serial interface card that has been selected for use in all ACCs. Mark is continuing work on the legacy interface software and the integration with the VMS software.
Local Oscillator
A 14 GHz Local Oscillator was successfully supplied via optic fibre to antennas CA03 and CA04. The major bulk of fibre optic cabling was done sometimes under atrocious conditions _ namely dust, heat, wet weather and flooding, mosquitos, spiders and snakes.
Leigh completed fibre optic cabling to all station posts with mains power available. Termination work in Screened room also completed. This was a massive effort by Leigh _ approximately 708 fibre ends spliced.
Receivers
The triumphs with the new mm-wave receivers are described elsewhere, but it's worth mentioning the large local effort contributed to the actual installation and alignment. Martin's report of his group's efforts is worth giving verbatim: "Lot's of blood sweat, stainless steel bolts and Daisy machining involved". [Daisy = Alan Day, cryogenics technician, machinist extraordinaire, and one of several Narrabri people involved.] Since installation, the systems have been available for extensive performance tests. Most of these have been lead by Ravi Subrahamanyan who has worked very hard to characterise the antenna optics _ alignment of primary and secondary reflectors and the receiver feeds.
Other Observatory work
Computing
John Giovannis has been working on upgrading the computer security on site, applying operating system patches and closing some security holes (with assistance from David Brodrick). This was prompted by a vacation student project to test our computer security. The preparations were successful and the students reported a secure system.
Scott Cunningham is finishing up his M.Sc. Thesis (on the Pulsar Machine) and continuing work on ATOMS.
Mark Wieringa has been dividing his time between AIPS++ bug fixes (quite a few uncovered lately) and ATOMS work.
Electronics
The Electronics Group has been very busy on a number of maintenance and renewal tasks, including: fitting new LNAs to the spare 6/3-cm receiver; adjustment of receiver turret cams; replacement of some crucial DC power supplies in the Correlator room; and numerous jobs at Mopra.
Engineering and Site Services
Visitors to the Observatory will have noticed the changes to the control building stairs. These stairs have long been known to not conform to building regulations - they were too steep and uneven. During the safety week in June last year Barry Parsons and Brian Wilkcockson rose to the challenge and proposed some improvements that could be made with minimal impact to the building and access to the upper level. Work commenced in December and will be completed early in 2001.
Other work in the engineering area includes the preparation of the final two "igloos" - cooling enclosures for the antenna cryogenics compressors. These will be installed in the next available maintenance period.
The grounds around the Compact Array tourist Visitors' Centre have been improved with a new wooden post and rail fence, which nicely finishes the new parking and roadway areas constructed last year.
Pulsar Backend
The last few months have seen outstanding progress with the Compact Array Pulsar Backend. This device will allow observations of pulsar profiles from the combined signal of all six antennas, giving a collecting area equivalent to a 54m dish. The Backend provides spectra with up to 1024 channels in each of 1024 points across the pulsar period. It operates at a number of bandwidths up to a maximum of 64MHz and can be used in any of the wavelength bands offered by the Compact Array. Martin Oestreich, Scott Cunningham and visitor Prof. A Deshpande from the Raman Research Institute, Bangalore, have forged ahead with the project and made some successful observations with a prototype operating on a single polarisation channel. Figure 2 shows the profile of pulsar J0437-4714 at 1410MHz.
Figure 2: Profile of pulsar J0437-4714 at 1410MHz.
Visitors Centre
There was a downturn in visitor numbers during September to October - possibly because of Olympics. November experienced another downturn because of flooding in the Namoi Valley.
WORK EXPERIENCE AT THE COMPACT ARRAY
Each year applications are received at the Compact Array from high school students Australia wide wishing to gain work experience positions. In the past it has been the practice to accept students one at a time in order to minimise the burden on the supervising staff.
During 2000 three applications arrived requesting a period in September and the question was asked, could we accommodate them? Although not immediately obvious it happened that the three applications were individual requests by students from the same school, Knox Grammar School, and each had acted independently without the other's knowledge. A quick check with the School's Science Master confirmed that the students were likely to get along with each other so the decision was made to accept their requests.
Realising that this was going to be quite a load on the observatory staff it was time to come up with a project that would give the students the experience they sought, be highly educational, and be able to be shared across different groups at the Observatory. After some deliberation it was decided that they could build their own radio telescope and the "RadioJove" project was selected.
"RadioJove" is a NASA project that is offered in America to school groups. The groups construct radio receivers and antenna systems from kits, conduct and record observations, analyse their data, and then share their results with other groups.
The three students, Robert Chapman, Anthony Smith and Roger Senior, were given fair warning of their project so they could gain an insight from information posted on the "RadioJove" web site (http://radiojove.gsfc.nasa.gov/). Five days is not a long period in order to complete the task.
Anthony Smith, Robert Chapman and Roger Senior of Knox Grammar School preparing their equipment for observations
On day one the students toured the Compact Array before familiarising themselves with the kit of parts and the tasks ahead. Day two saw Roger constructing the receiver while Robert and Anthony set about constructing a phased array dipole antenna system. Day three was spent aligning, tuning and testing the system.
Day four commenced at 3:00 am with Jupiter high in the sky. Hisses, crackles and plops were all recorded but unfortunately the noise of the recorder masked any results that may have been obtained. The rest of the day was spent determining system temperatures and tweaking.
On the final day the students were able to record directly to a lap top computer and the results were encouraging. Data analysis under the guidance of the OIC indicated that they had successfully measured the temperature of the Galactic Plane to within 30 per cent of the true figure. Not bad using such a simple system!
The "RadioJove" receiver and tape recorder
On the afternoon of the fifth day the students disassembled the equipment and readied it for a journey to Sydney where all students of Knox Grammar School can employ it. Feedback from the students indicated that they had enjoyed a very rewarding and educational experience whilst at the Paul Wild Observatory that would go a long way when they finally make decisions on their future careers.
Dave McConnell
Officer-in-Charge
(dmcconne@atnf.csiro.au)