# Australia Telescope Development Plans

As at 2003 Feb 28

Introduction

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## Introduction

The Australia Telescope Future Development Plans are based on inputs from the user community and the ATNF astronomers and engineers. This document gives a short scientific justification for each proposed development and a description of current status. In many cases, more extensive documentation is available. Developments supported by funding from the Major National Research Facilities (MNRF) grant received by the ATNF in December, 1995, are indicated. The developments are not listed in priority order.

A companion document to this plan is a spreadsheet of forward planning and budgetary estimates for the next five years, maintained separately by the ATNF Future Developments Programme Manager (J.W. Brooks). This spreadsheet lists a priority for each item, assigned by the AT Users Committee (ATUC) on the basis of scientific merit, and approximate estimates of the total costs of each project, including past expenditure.

The priorities are reviewed by ATUC regularly (at least annually). For the higher priority projects more detailed costing and manpower estimates have been made by the ATNF Engineering Staff and the development has been distributed over the next five years based on the scientific priority, availability of appropriate manpower and the budget. In later years the estimates are less accurate and a more detailed balancing of budget and manpower has not been attempted. The total resources requested for future years is greater than the available budget so some items will have to be cut down or moved to later years depending on scientific priorities.

A second companion document is the list of completed projects

In this issue (2003 Feb):

At this meeting, we note the retirement of John Brooks, who has done a terrific job of managing the Future Developments Program. Dave McConnell and Warwick Wilson will take up different aspects of this task.

V.J. McIntyre, ATUC secretary

## 1. Australia Telescope Compact Array

Project Leader: R. Subrahmanyan, C. Murphy
Proposed: 2001 Feb 1  Funding:  not_funded

For 3mm observations, it is anticipated that dynamic positioning of the antenna subreflectors may be required. However the current positioning system may not be adequate for long periods of continuous adjustment.

Status: not_started  (updated 2003 Feb 27)
A detailed study of the deformations of the main reflector was made during 2002 (see ATNF memos 39.3/113, 39.3/115 to 39.3/117, available here). The conclusion is that by two axis adjustment of the subreflector will result in significant improvement in gain and beamshape. Preliminary designs are being developed for the two-axis control, and components ordered.

### 1.2. Wideband (8GHz) continuum correlator

Project Leader: W. Wilson, Project Scientist: R.D. Ekers
Proposed: 2000 Oct 26  Funding:  triennium

The wide bandwidths available with the new MMIC receivers at 12 and 3mm and having the means of transmitting these wide bandwidths through the new fibre optic signal distribution system, together with the wide band analog correlator designs being developed for AMIBA open a window of opportunity for the ATNF to implement a 8-16GHz continuum backend for the ATCA.

Status: on-going  (updated 2003 Feb 26)
Successful observations were carried out at 18GHz with a 30-metre baseline single polarisation system in September 2002. This system used an analogue correlator with a 3.5GHz bandwidth. In 65 hours of survey time, 1000 square degrees of sky were covered, achieving a sensitivity of 35mJy in an 80 millisecond integration time. An extension of this system to three baselines and 8GHz bandwidth is proceeding. It is expected that the new system will be available for testing in September 2003.

### 1.3. Atmospheric seeing monitor

Project Leader: R.J. Sault, Project Scientist: M.J. Kesteven, Project Engineer: G. Graves, B. Reddall, C. Murphy
Proposed: 1999 Sep 1?  Funding:  triennium?

A dedicated atmospheric seeing monitor will be invaluable in making scheduling decisions for the millimetre-wave ATCA, as well as allowing long-term accumulation of seeing statistics. While alternative instrumentation and techniques currently exist, the accumulation of long-term statistics has largely floundered because of the need for on-going staff attachment at the Observatory. An interferometric monitor of the type envisaged should be a more straightforward instrument to operate and interpret, and it is expected that the cost of constructing an instrument to observe continuously the beacon (or other) transmissions from geostationary satellites should not exceed \$30k.

Status: on-going  (updated 2003 Feb 27)
Funding has been secured, the design of the system is complete and components are being purchased. The system will use the holography receivers, specially-purchased antennas, and various parts of the array infrastructure. The seeing monitor antennas will be located north of stations W128 and W113. The target completion for the system is winter 2003.

### 1.4. Antenna CA06 to 3km arm

Proposed: 1999 Mar 23  Funding:  not_funded

This proposal is to provide a transport system that would allow movement of the sixth antenna of the Compact Array onto the 3km track, and back again. Having six antennae on the 3km track would improve imaging speed at high frequencies.

Status: no action  (updated 2001 Feb 17)
A feasibility study was done by Connell Wagner; their report is available from Bruce Thomas. The cost was found to be high, and any further action awaits an opportunity to access capital works development funds.

### 1.5. Next generation spectral line correlator

Project Leader: W. Wilson, Project Scientist: J. Caswell
Proposed: 1999 Mar 5  Funding:  mnrf2001

This is a project to replace the ATCA correlators with a new design to increase the maximum available bandwidth from 128 MHz to 2 GHz, with the capacity to provide all 4 Stokes polarization parameters for 2 separate centre frequencies (2 IFs, with separation limited only by the instantaneous bandwidth of the amplifier front-end/feed system). The necessary redesign of much of the IF system is regarded as part of this project. Furthermore, the new benefits will be considerable at all of the narrower bandwidths currently available on the existing correlator.

The basic concept envisaged is for a 2-GHz portion of the spectrum to be subdivided into a maximum of 2048 channels as a first processing stage. Then, further processing will be available to yield a spectrum of much higher resolution for any one portion of this subdivided spectrum. The number of antennas that can be serviced by the correlator will be at least 8 and thus allows for at least 2 new elements to be added to the compact array over the correlator lifetime (specifically allowing for the integration of new SKA prototype elements into the array).

Whereas the present number of channels available across a 4-MHz bandwidth is limited to 1024 channels if 4 stokes parameters are recorded, the new correlator is expected to generate a 8192 channel spectrum (in each of the 4 polarization parameters). Most likely, this high resolution capability will be simultaneously available at several regions within the basic 2-GHz spectrum.

For example, we would expect that an 8192-channel spectrum across 4 MHz in each of the 4 Stokes parameters would be simultaneously available at 1720, 1666, 1612 and 1420 MHz.

As another example, in the 16 to 26 GHz band, we may expect to simultaneously study water masers, several transitions of methanol and/or ammonia, and atomic recombination lines.

The astronomical capabilities are similar to those envisaged by NRAO for their desired VLA replacement correlator, see for example Rupen 1997 on http://www.nrao.edu/ following links to: vla expansion project; technical development; correlator

Status: on-going  (updated 2003 Feb 26)
The overall project involves an upgrade of the ATCA IF and backend system to provide a maximum bandwidth of 2GHz on 4 IFs for both continuum and spectral line observations. The correlator uses a new concept where each antenna signal is split into many channels in a polyphase digital filter bank. Fringe rotation and fine delay rotation are done in the filter bank. The filtered digital signals are then correlated channel by channel. A proof-of-concept polyphase digital filter bank is being developed. This device will be ready for testing in mid 2003.

Project Leader: G. Moorey, Project Scientist: R.D. Ekers
Proposed: 1999 Feb 28  Funding:  not_funded

This frequency band is the highest for which the AT antennas were designed to operate at the full 22m aperture. In general terms this band, covering 30-50GHz, will offer the observer access to a number of transitions of molecules like SO, SO2, SiS, C2S, SiC4, OCS, SiO, CS, C3H2, HDS, H2S, methanol (CH3OH) (and their isotopes) and a large number of carbonhydrates (like CH3OCH3, CH3CH2OH etc). Furthermore, this band is suited to access medium (z=1-3) and high (z=3-5) redshifted lines of CO, HCO+, HCN, hydrogen recombination lines etc.

It should be pointed out that a large number of lines in this part of the spectrum have not been identified and conversely the 7mm transitions of many molecules have not been calculated. Most of these transitions trace different temperature and density regimes of the interstellar medium. Other transitions, like methanol (CH3OH) and SiO give detailed information on the kinematics of the stellar disks, stellar jets and stellar envelopes.

Furthermore, the 7mm band is widely used as a continuum band for short and long-baseline arrays to measure the structure of jets and accretion disks in the inner parts of active galactic nuclei, as well as for studies of galactic objects like flare stars, stellar winds from hot stars and supernova remnants.

As examples, this band will be interesting for studies in:

• Interstellar medium: the structure, chemistry and kinematics of dark clouds
• Star formation: the structure and kinematics of proto-planetary disks
• Evolved stars: mass-loss rates and kinematics of stellar envelopes
• Astro-chemistry of carbon-based molecules
• Galactic continuum: supernova remnants, radio stars, X-ray novae
• Extra galactic: absorption and emission lines of highly red-shifted objects, structure of gravitational lenses, structure of jets and accretion disks in active galactic nuclei, structure of interstellar medium in nearby galaxies, and the Magellanic Clouds
• Anisotropies in the cosmic microwave background, Sunyaev-Zeldovich effect.

The instrumentation of just two adjacent ATCA antennas with 7mm receivers would still allow much valuable science to be addressed, including participation in the proposed Japanese VERA project at this frequency. The VERA project aims to measure accurate parallaxes of Galactic H2O and SiO masers by using a pair of telescopes at a number of Japanese VLBI observatories to observe the maser and a phase-reference source simultaneously. The addition of the long baselines to the ATCA will make a significant contribution in this challenging attempt to map the Galaxy in 3 dimensions.

A second obvious application of a simple interferometer is the measurement of continuum flux densities of discrete sources to complement the proposed experiments in Antarctica to measure the microwave background fluctuations. Such flux density measurements would not be feasible without an interferometer.

Current designs for the 12/3mm receiver package include a spare slot for later retro-fitting of 7mm horn and receiver, but make no provision for concentric (i.e. simultaneous) observing in any two of the bands.

Status: no action  (updated 2003 Feb 26)
Currently no funding for the full 7mm system (7 units). However a number of MMICs for the 7mm band have been designed and tested under the ESP programme. The design and construction of the ATCA 3/12mm Receivers takes into account the installation of a 7mm system, including cooled hardware and a location for the 7mm feed-horn. This project, together with the real-time fibre link between Mopra and the ATCA, was the second highest ranked, currently not funded, project coming out of the +20% Triennium funding deliberations by the AT Users Committee (see the ATUC Report from March 1999).

### 1.7. Phase correction system (water vapour radiometer)

Project Leader: R.J. Sault, Project Scientist: R.J. Sault, Project Engineer: G. Carrad
Proposed: 1996 Nov 1  Funding:  mnrf1997

Synthesis imaging at short wavelengths (less than about 3cm) is severely affected by atmospheric phase instabilities. The effects of these can be limited by restricting observations to periods of good weather conditions, but even then the instrumental phase noise limit (at least that expected after the LO upgrade) is not achieved. Correction for atmospheric phase fluctuations will be essential for observations in the 3mm band and important at longer wavelengths. Such corrections are also important for astrometric VLBI measurements. The general area of atmospheric phase correction is a fast-moving area of radio science and, after a series of engineering and scientific studies, it is likely that the ATCA phase correction will rely on two complementary schemes:

1. relatively fast (approx. 1min cycle) position switching of the antennas will "stop" the slower tropospheric fluctuations;
2. a radiometric phase correction (RPC) scheme will deal with fluctuations on timescales down to 1s.

Status: on-going  (updated 2001 Oct 11)

The radiometer design is a 4-channel 22GHz system which is distinct to the main astronomy receiver packages. Each radiometer uses a separate horn that is mounted close to the astronomy horn (the offset between radiometer and astronomy horns is approximately 5 arcminutes). Two prototypes, developed for evaluation, were delivered in October 2000. The (uncooled) amplifiers and detectors have been developed by Astrowave Pty Ltd, and the data acquisition system consists of two laptop computers connected to the control building via ethernet.

Progress on this project has largely stalled. In 2002, two separate people attempted to make progress understanding the limiting errors in the system. However these remain poorly understood. Since October 2001, the only significant progress has been to develop software to log water vapour radiometry output using the new ACCs. This eliminates the need for the laptops. It is now straightforward to collect the WVR output whenever the 12 or 3-mm systems are on axis, which will allow WVR data to be sampled and analysed more readily. It is intended to use these capabilities during the winter of 2003 to improve our understanding of the behaviour of the WVRs. No decision will be made to develop new radiometers until we are comfortable that we understand or can live with the errors in the existing pair.

Project Leader: G. Moorey, Project Scientist: T. Tzioumis, Project Engineer: G. Moorey, G. Graves
Proposed: 1996 Jan 1  Funding:  triennium

Following the success of the 6/3cm upgrade, it is proposed to upgrade the 20 and 13cm amplifiers in all antennas. Experience with upgrading the Mopra antenna shows that substantial (approximately 30%) reduction in system temperature is possible, particularly beneficial for spectral-line measurements.

Additionally, tests have disclosed that the current ATCA 13cm feed systems exhibit poor off-axis polarisation properties, severely degrading the imaging of extended sources in this frequency band. A retro-fit of redesigned 13cm ortho-mode transducers on the six ATCA dishes would eliminate this problem.

Status: on-going  (updated 2003 Feb 25)
G. Graves has tested a modified polariser, with sin4 tapered fins, better matched probes and a modified back-short. This appears to perform well. Production of improved polarizer components is on hold due to more pressing tasks. As regards the LNAs, one option is to replace the existing 20cm LNAs on the ATCA with amplifiers of the same design as proposed for the Arecibo multibeam contract. Another option, more compatible with the CABB upgrade, is to install 1-3GHz LNAs thus eliminating the diplexers. P. Axtens is investigating a new 13cm (1-3 GHz) LNA design.

### 1.9. Optical Pointing

Proposed: 1996 Jan 1?  Funding:  not_funded

The pointing of the antennas becomes more critical at shorter wavelengths. Present practice at cm-wavelengths is to define a local pointing solution using a nearby calibration source (reference pointing) but this may not be feasible in the mm-bands where suitable sources are more difficult to find. Alternative solutions such as guiding with small optical telescopes attached to the antennas may need to be pursued further.

Status: no action  (updated 2003 Feb 26)

The advances made with reference pointing (D.McKay; D.Rayner) suggest that the optical pointing may not be needed, particularly in the form originally proposed. There will be a further round of experiments with one telescope, but the matter is still quite open as to the extension to the array.

The project is on hold at this stage. There is no funding for it.

Project Leader: M. Leach, Project Scientist: R. Subrahmanyan
Proposed: 1995 Jan 1  Funding:  mnrf1997

The existing Local Oscillator distribution system is not stable enough for operation at mm wavelengths. The present system also requires considerable maintenance in order to allow reliable operation, even at low frequencies. It is envisaged that a local oscillator, based on distribution via single mode fibre, be installed. The goal is 10$o$ rms instrumental phase deviation at 90GHz, together with greater reliability.

Status: on-going  (updated 2003 Feb 21)
Since March 2002, all compact array antennae are running on the new fibre Local Oscillator distribution system. This includes a high frequency (currently fixed at around 13GHz) reference signal for the 12mm and 3.5mm systems on antennas 2, 3, & 4. All array stations are now available. The new array stations on the north-south spur were used for the first time during the May Observing term.

Antenae 1, 5 and 6 are scheduled to be fitted with 12mm receiving systems and High Frequency Local Oscillator systems in early April 2003. Frequency agility (no more module swaps!) for the High Frequency reference is expected to be available by the end of May 2003.

### 1.11. 15-22m surface extension, measuring equipment, studies

Proposed: 1995 Jan 1  Funding:  mnrf1997

For 3mm observations, the current surface of the Narrabri antennas is only usable to 15m diameter. The outer section of the antenna has perforated panels which are largely transparent at frequencies above 60GHz. This results in lower forward gain and increased system temperature, compared to a non-transparent 22m antenna. Since the backup structure appears stiff enough we have started to replace the outer surface to allow operation to 22m. This will significantly improve the scientific capabilities of the antennas.

The plan is to retain the shaped surface, as this is the simpler engineering solution. The penalty is a reduced off-axis performance; this is acceptable for the Compact Array, although it would seriously compromise the single dish performance. Operation with focal-plane arrays, or frequency-switching between off-axis feeds, will require either reshaping the reflector or the use of phase-correcting optics.

The extension would render not only greater sensitivity (approximately double) to point sources, but would allow mosaicing of the full primary beam; an important consideration for sources of extended emission. The increase in sensitivity at this frequency is particularly important given the coherence limitations that may be imposed by the Narrabri site.

Holographic imaging is the only viable method of setting the antenna surface to the correct figure. An initial round of panel setting used the Optus-B series of satellites at the frequency of 12.75 GHz, and achieved a surface rms of 0.2 to 0.3 mm. For the final setting, it is proposed to build two 30GHz radiometers for use with the Optus B3 geostationary satellite. These radiometers will be used at Narrabri, Mopra, Parkes and other LBA sites for holographic imaging.

Status: on-going  (updated 2003 Feb 24)

New solid panels have been built for Mopra and the 5 antennas of the AT Compact Array. The panels have a surface accuracy of 100 microns. The panels have been installed at Mopra and five antennas of the ATCA.

New holography equipment, operating at 30GHz, has been built by Astrowave Pty Ltd (completed in early 2002). The two 30GHz receivers are based around the low noise, room temperature amplifiers from Mitec. In 2002 a 12GHz holography system (receivers by George Graves, backend by Astrowave) was also constructed. The beacons are the Optus B1 or B3 satellites, which is used depends on their current orbit.

Holograms are made at night; several are needed, to guide the tweaking which would be done during the day. A full survey and adjustment cycle takes about a week to complete. Two dishes (ATCA Antenna 2 in Dec 2002 and Mopra during winter 200) have now been surveyed with 30GHz holography. We achieved an initial panel setting of better than 200 microns rms. This corresponds to a Ruze efficiency of 60% at 86 GHz, to this must be added the other loss factors, such as blockage and illumination. On the basis of this survey, the surface of CA02 will be adjusted in March 2003. Plans are being made to survey and adjust ATCA anntennae 3 and 4 at the end of May 2003. Holographic surveys of Parkes (12GHz) will be done as part of the panel upgrade in March/April 2003.

In early 2002, a new technique was attempted, optical photogrammetry. This provides measurements of the dish shape and subreflector position, independent of the optical train. The method is fast and effective, with precision of well under 1mm, and can be done during the day. It shows deformations of the surface with elevation are modest. There is a small movement of the subreflector, which is described in AT Technical Memo 39.3/117 (PDF, 1.4Mbyte) by Ravi Subrahmanian.

On the basis of the photogrammetry, it now appears it will be possible to make routine movements of the subreflectors to compensate for surface deformations. The subreflector will move along the symmetry axis and will rotate about a horizontal axis (equivalent to a sideways shift, for small shifts, and easier to implement mechanically). The tipping mechanism is being designed, and is expected to be availble for at least part of the mm-wave observing season.

Project Leader: G. Moorey, Project Scientist: B.S. Koribalski, Project Engineer: G. Moorey, G.R. Graves, M.A. Bowen
Proposed: 1994 Nov 1  Funding:  mnrf1997

The region from 80 to 115GHz is rich in molecular spectral lines with over 500 known transitions. Although the CO molecule at the top end of this band is important, limitations of the site (atmospheric absorption and phase instability) and of the telescopes (reduced efficiency) might limit satisfactory observations at this frequency. We plan to equip all six antennas of the Compact Array with receivers based on InP MMIC technology. Satisfactory imaging with this system will depend on improvement of the telescope efficiency and on phase correction and will only be possible on clear non-summer nights. Weather statistics indicate that these conditions apply for more than 30% of nights for more than six months of the year. Beam-switching to a lower frequency will also be possible on timescales of minutes as an additional method of phase correction as well as giving access to other bands for observations in their own right. All three mm-wave systems (3, 7 and 12mm) will be within the one dewar to facilitate switching between these bands.

Status: on-going  (updated 2003 Feb 26)

As of Oct 2001, there are three prototype 3.5mm receivers installed at the ATCA (on Antennas 2, 3 and 4). They have a fixed tuned LO, frequency 80.5055 GHz. The sky frequency coverage is 84.906 to 87.305 GHz using the C-Band Splitter module and 88.506 to 91.305 GHz using the X-Band Splitter module. The system temperature over the 85 to 87GHz band is ~250K and over the 88 to 91GHz band ~200K.

Manufacture of components for the production 3.5mm system is proceeding. The exact frequency coverage of the production system will be a little uncertain, until the system is integrated and undergoes frequency response testing (in late 2003).

The first production 3.5/12mm receiver tested in January was fitted with the new W-band OMT and a set of type 100LNA-02A W-band LNAs (from CSR15 ESP wafer run). Only one polarization was used, the other port of the OMT was terminated. The 100LNA-02A MMICs are used in the existing 3.5mm receivers. Testing revealed a useful frequency band of 85 to 112GHz but with a mismatch ripple at the lower end. Receiver noise temperature was ~85K across the band centre, increasing to around 150K at the band edges.

A prototype waveguide coplanar LNA design MMIC (100LNA-05A) was included on CSR15 wafer run. This yielded 5 devices, two of which have been packaged and await testing. Testing is on hold while our 100GHz Vector Network Analyzer is being repaired. This instrument is used to test all circuits working above 20GHz. Larger numbers of (production) devices were fabricated on the recent CSR17 FARADAY wafer run.

The production schedule and integration of the subassemblies for the 3mm receivers is being driven by the development of the doubler chains for the 100GHz Local Oscillator. The two critical components still under development jointly by CTIP and ATNF are the 30-50 GHz and 90-104 GHz power amplifiers.

Project Leader: G. Moorey, Project Scientist: R. Manchester, Project Engineer: G. Moorey, M.A. Bowen
Proposed: 1994 Nov 1  Funding:  mnrf1997

Currently, the highest frequency available on the Compact Array is 9.2GHz (3cm band). A receiver system, operating from at least 16 to 26GHz, will provide increased angular resolution for continuum observations and give access to some very important spectral lines.

• With the full 6km array, resolutions of 0.3 arcsec will be possible, probably giving the highest resolution high-dynamic-range images attainable with the Compact Array, important for objects such as SNR 1987A. The lower end of this band is also ideal for observations of arcminute scale anisotropies in the cosmic microwave background.
• The most important spectral lines covered by the proposed band are at 22.2GHz (H2O maser) and 21.7-25.1GHz (ammonia) and around 25 GHz (methanol). Other weaker lines from more complex molecules such as cyclopropenylidene (at 18.3GHz) are also within the band. These molecules are all widespread in galaxies, some are very strong, and all are important for studies of molecular clouds, star-forming regions and galaxy dynamics.
• This band covers the highest frequencies available on the majority of the Australian LBA telescopes. Use of the tied Compact Array in such VLBI arrays will give good sensitivity at the highest possible resolution. This is especially important for studies of Galactic and extra-galactic H2O masers and compact cores of active galaxies and quasars. NGC4945 and the Circinus galaxy are excellent candidates for studies of H2O megamasers which may be similar to those in the nuclear accretion disk of NGC4258.

Status: on-going  (updated 2003 Feb 26)

Three pre-production receiver systems covering 16-26 GHz have been completed and installed on the ATCA.

The InP LNAs and receiver can cover the band 16 to 26GHz when a tunable LO is installed. As of September 2001 the sky frequency coverage with a fixed LO of 26.8885GHz is 16.089 to 18.888GHz using the X-Band Splitter module and 20.089 to 22.488GHz using the C-Band Splitter module. The System Temperature over the full 16 to 23GHz band is ~60K.

Manufacture of the production systems is proceeding. The first of the production receivers has passed its laboratory tests. The second and third will be tested in the first weeks of March 2003. These three new production receiver systems will be installed at the ATCA in April 2003. These will be fully tunable over the 16 to 26 GHz range. There will be a major upgrade of all the exising 20/13 and 6/3cm conversion systems, with new Interface Modules, to eliminate the need for "module swaps". Extensive modification to the LO system will also be carried out. The three existing 12mm receivers will be modified with production sub-modules to eliminate module swapping.

## 2. Parkes 64m Telescope

### 2.1. Pulsar extension of Multibeam Correlator

Project Leader: E. Davis, Project Scientist: R. Manchester
Proposed: 2003 Feb 03  Funding:  not_funded

A modification to the Parkes Multibeam correlator using the subsystems and techniques developed for the Wideband Pulsar correlator to permit pulsar observation at 64MHz bandwidth with the Parkes 10/50cm receiver. Similar units can be assembled for use other AT observatories or observatories that have procured AT Multibeam Correlators.

Status: preparing  (updated 2003 Feb 03)
Initial design underway

Project Leader: M. Kesteven, Project Scientist: M. Kesteven
Proposed: 2002 Jun 1?  Funding:  contract

As part of the JPL tracking contract, the outer panels of the Parkes dish needs to be upgraded so that the entire surface can be used at 8 GHz.

Status: on-going  (updated 2003 Feb 26)

Contract for panel manufacture has been let to a Sydney engineering company with substantial experience in antenna and panel manufacturing. They will produce 192 panels with surface rms of <0.25mm. Delivery is scheduled for early March 2003, installation and surface configuration will take of order 1 month.

To facilitate surface adjustments, a new holography processor has been built and was tested (successfully) in June. Parts for upgrading the 12 GHz holography receiver have been ordered, a trial run is expected to take place in Jan 2003.

### 2.3. JPL 8 GHz receiver

Project Leader: G. Moorey, Project Scientist: ?
Proposed: 2002 May 1  Funding:  contract

This project is to design and build an 8 GHz receiver and down-converter, for NASA/JPL tracking work at Parkes.

Status: on-going  (updated 2003 Feb 14)

The NASA requirements are for 8.4GHz with 100MHz bandwidth, but our design will be capable of 2GHz, thus providing a very low-noise receiver for astronomy. The dewar design will also incorporate cold hardware and hermetic connectors to enable the installation of 2.4GHz LNAs at a later date.

Bruce Thomas produced a feed design which to illuminate 54m of the Parkes surface. This has now been manufactured, tested and found to meet the design specifications.

Design and simulation of the quarter-wave plate and Ortho-Mode Transducer with waveguide outputs is finished. Manufacture has commenced. A new design for a LNA with waveguide input is complete and manufacture has begun. Design of the frontend frame and dewar continues. Two 8GHz downconverters specified by JPL, containing the phase lock and LO, have been built and delivered by Miteq. Image reject filters have been designed and are being built. The electronics for bias, control and monitoring have been designed and construction has started. All other components, including a CTI-1020 helium refrigerator are in hand.

This project was moved to the Parkes section of the development program listings, as it will improve the capabilities of the telescope beyond the end of the contract observations.

### 2.4. 6GHz focal plane array

Project Leader: G. Moorey, Project Scientist: J.L. Caswell
Proposed: 2001 Feb 1  Funding:  triennium
jointly with jbo

A Multi-beam system with 7 feed horns, covering the frequency range 6.0 to 6.7 GHz is planned. This is a joint project with Jodrell Bank Observatory.

The prime scientific objective is a sensitive unbiased survey of the Galactic plane for masers at the 6.6-GHz transition of methanol. At Parkes, the spectrometer will be the existing MultiBeam correlator, concatenated to give 2048 channels for each polarization on each of the 7 beams. A survey taking several months at both Jodrell Bank and Parkes could cover the full Galactic plane with latitude coverage +/- 2 degrees, with a detection limit better than 1 Jy (5-sigma). Such an unbiased survey could expect to at least double the number of known methanol masers to more than 1000, and deeper surveys could be envisaged where appropriate. The detected masers would provide a definitive census of regions with ongoing massive star formation throughout the Galaxy, and these in turn would be superb targets for follow up at both mm-wavelengths and the IR (initially with existing facilities such as Mopra, SEST, the upgraded ATCA, and subsequently with ALMA, SOFIA, and space IR missions).

Timescale: the Jodrell observations await the upgrade of the Lovell telescope, available 2003; ATNF resources are currently focused on completion of mm-receiver installation on the ATCA. Barring unforseeable delays the full system may be ready for testing at Parkes at the end of 2003.

For comparison with the HI MB system, note that this is a much smaller receiver package (at less than one-quarter of the wavelength, and with only 7 beams rather than 13). System parameters are excellent for several other projects: the lower end of the frequency range encompasses transitions of excited OH that are often prominent masers in Star Forming Regions. Pulsars tend to be weak at this quite high frequency, but the reduced scattering will make the receiver of special value for some pulsar observations.

Status: started  (updated  2003 Feb 26 )
CTIP have a contract to determine the feed spacings for the Parkes and Lovell telescopes, and to manufacture seven feeds plus the front support plate for Parkes. The spacings have been determined and the feedhorn designs are undergoing a final tweak before release. Upon completion of the parks feedhorn design, a prototype will be built and tested before the full production starts. Little progress on receiver design and construction, we are waiting for delivery of an OMT and LNA from Jodrell, before proceeding.

Project Leader: R.N. Manchester, Project Scientist: R.N. Manchester
Proposed: 2001 Feb 1  Funding:  not_funded

This is project has been split off from the Parkes 10/50cm receiver development. At those frequencies RFI is likely to be quite strong, and dynamic, adaptive excision techniques will probably be needed. This project is an exploration of those techniques.

Status: not_started  (updated 2001 Feb 17)

### 2.6. 22/32GHz focal plane array

Project Leader: W. Wilson, Project Scientist: L. Staveley-Smith
Proposed: 2000 Jul 1  Funding:  not_funded

A high frequency multibeam receiver on the Parkes telescope would allow sensitive line and continuum studies of Galactic and extragalactic sources. A modest 13 beam system would allow the existing correlator to be used for Galactic line observations. However, the f/D ratio of Parkes is greater at this frequency, so more beams can be added. 19 beams could be accommodated with a minor correlator upgrade. More (37, or perhaps 61) may be possible for continuum-only observations.

The scientific rationale is:

• The sites of future star formation: large-scale surveys of NH3 in cold Galactic clouds
• The sites of current star-formation: a Galactic survey for water masers
• The proper motion of the Magellanic Clouds: surveys for water masers in the LMC and SMC
• The Distant Universe: an all-sky survey for radio continuum sources (around 20,000 sources brighter than 20 mJy are predicted).
• A catalogue of high frequency sources for ALMA and ATCA calibration purposes.
• Deconfusion of intrinsic CMB anisotropy experiments.
• Large-area blind SZ survey for distant, massive clusters.

The above science capabilities are based on a minimal (13 or 19) beam system with a continuum bandwidth of 5 GHz (16-21 GHz) and an InP array with T(sys)=70 K.

Status: not_started  (updated 2001 Oct 15)

### 2.7. Parkes baseline ripple

Project Leader: ..., Project Scientist: L. Staveley-Smith
Proposed: 1999 Mar 23  Funding:  not_allocated

This project is an investigation of what could be done to reduce the level of baseline ripple in the Parkes telescope. Experiments with absorbing material attached to the underside of the focus cabin showed that the ripple could be reduced, though this came at the cost of increased system temperature (a few Kelvins).

Status: no action  (updated 2003 Feb 14)
The details of the experiments, and various other engineering options, are given in ATNF technical report 39.3/084. No-one is assigned to lead this project.

### 2.8. Wideband pulsar correlator (1 GHz)

Project Leader: E. Davis, Project Scientist: R.N. Manchester
Proposed: 1998 Jan 1  Funding:  triennium?

A new correlator and digitiser system based on the SEST correlator has been developed for use primarily in high time-resolution pulsar observations. Low-cost RISC processors are used to synchronously average the data at the pulsar period. This instrument will be capable of handling wide bandwidths (up to 1 GHz) and is a versatile instrument capable of data acquisition for pulsar timing, scintillation, polarimetry and searches.

Status: on-going  (updated 2003 Feb 27)
The system is now largely commissioned and will be made available for general use in the September 2003 term with some restrictions on operational parameters. Burst mode and search mode require further development work.

Project Leader: G. Moorey, Project Scientist: R.N. Manchester
Proposed: 1997 Nov 19  Funding:  triennium

A dual-band dual-polarisation receiver system for Parkes covering the 10cm (2.6 - 3.6 GHz) and 50cm (640 - 704 MHz) bands is under development. The primary motivation is to provide a system optimised for pulsar observations, but the receiver would also be useful for other wide-band continuum observations and would cover the 3.3GHz transition of CH and various recombination lines. The bands have been chosen to avoid known or anticipated sources of narrow-band RFI.

The aim is to provide wide-bandwidth systems with lowest possible noise temperature. Both the GBT and the up-graded Arecibo will come on line in the next year or two. The multibeam receiver has given us an unrivalled instrument for pulsar searches. However, a system allowing us to make follow-up observations, especially timing and polarisation studies, with high efficiency is essential for us to remain competitive.

The dual-band dual-polarisation feed system for this receiver has been designed by C. Granet, H. Z. Zhang, K. J. Greene and G. L. James (TIPP 847, September, 1999) and is presently under construction. It will have close to optimum G/T for the Parkes antenna and excellent polarisation isolation.

It is planned that the 10cm receiver will be used with the wide-band pulsar correlator. Part of the Multibeam correlator will be configured to provide polarization capability over the 64MHz bandwidth of the 50cm receiver. Both receivers will also work with the existing filterbanks.

Simultaneous operation of these two systems is compatible with the Parkes down-converter system. Because of the RFI environment at these frequencies, a separate development project on adaptive RFI cancellation is running in parallel with this work.

Status: on-going  (updated 2003 Feb 14)
Construction of the receiver is now well under way. The feed is complete, as is the receiver package. Internal dewar components are being fabricated and assembly continues. Mechanical location tests (to verify the two major components fit together accurately when hoisted separately into the receiver cabin) were carried out in mid-February 2003, with great success. The problems of receiver rotation were solved and a respectable range of +/- 90 degrees of rotation was achieved. All RF and electronic components are in hand. Installation and commissioning of the receiver are planned for August 2003, construction progress is only governed by the availability of staff due to higher priority projects.

### 2.10. Telescope drive system

Proposed: 1997 Jul 1  Completed: 1997 Jul 1  Funding:  triennium

The Parkes telescope relies for pointing and other essential control functions on a series of aging and underpowered microcomputers which present problems of maintenance both in hardware and software. The progressive replacement of these systems will improve reliability and allow easier maintenance and greater functionality of the telescope control system.

Status: on-going  (updated 2003 Feb 26)
This project is proceeding as time permits whilst ensuring that the present control system remains fully operational. Several upgrades to the present system have been made or are in progress. These include the following:

• A revision of the sequence for operation of the jacks to prevent the system becoming confused when an astronomer changes his/her mind about applying or releasing them
• Software modifications to the SERVO code to cope with changed motor-currents following the refurbishment of the gearboxes
• Modification of the brake release circuitry to ensure telescope safety - recent cable failures caused unwanted release of the zenith brakes by the by the azimuth brake-release circuit when the dish was parked in zenith on its brakes. Fortunately disaster was avoided because the dish was less than a degree from the stop when this happened. Several hours were spent investigating the problem and some circuit changes were made to prevent its recurrance. Further circuit modifications and installation of new monitoring equipment is going to take place during the March shut down to detect future cable failures and prevent any similar events in the future.
• Software modifications to the ME code to better cope with loss of the distributed clock signal and provide proper better error messages to the astronomers in case of clock and communication failures in future.

Other work that needs to be completed on the way towards implementation of a new drive-control system includes relocation of the ME drive electronics from the computer room into the ME mount - space is now available for this following the replacement of the old encoders with the new ones. Completion of the installation of the pneumatic jack operation hardware is also on the agenda for the near future.

Project Leader: W. Wilson, Project Scientist: J.L. Caswell
Proposed: 1997 Mar 14  Funding:  triennium

This project is an investigation of ways to to improve spectral-line capabilities at Parkes. Enhanced capabilities would have important scientific benefits in several important astrophysical areas, including star formation and extragalactic megamasers. Masers in star formation regions have long been recognised as extremely useful for;

• recognising the sites of massive new-born stars,
• studying these sites with high spatial (centi-arcsec) and velocity (0.1km/s) resolution
• studying the embedded magnetic fields through polarisation measurements of Zeeman splitting,
• assessing densities, temperatures, densities, chemistry and radiation fields in these environments by comparing masing transitions of different transitions and species (many transitions of OH, methanol and water)
• observing time-varying phenomena, including large scale kinematics through proper motions, and interpreting these in terms of 3-d structures.

Single dish observations remain remarkably useful in complementing full VLBI studies, by efficiently providing detailed spectra and revealing variability. Note that the Compact Array cannot achieve this for 1.6GHz OH because the size of its correlator which, spread over 15 interferometer pairings, is much too small to provide adequate frequency resolution and polarisation data.

The requirement for OH maser work is simultaneous observations at both the 1665 and 1667MHz transitions, all four Stokes parameters, with frequency resolution after Hanning smoothing of 1 kHz (0.5kHz before smoothing). An S2-DAS system, installed in March 1998, provides up to 2 IF channels at bandwidths of 64 and 32 MHz and up to 4 IF channels at bandwidths from 8MHz down to 0.064MHz. Combining the S2-DAS with the multibeam correlator could achieve these ends by concatenating the sixteen correlator boards four at a time to give four autocorrelations each with 8000 spectral channels. Development of the multibeam correlator in this way would also be useful in studying water masers and ammonia near 22GHz.

Specifically, for water masers, 32MHz coverage could be obtained with 8000 channels and thus a capability (in terms of radial velocity coverage and resolution) similar to OH at 1.6GHz. In this instance the wide bandwidth is needed to study the high velocity features often present and it could prove efficacious to sacrifice resolution by a factor of 2 in order to provide velocity coverage of 800km/s (64MHz). For ammonia the ability to observe two transitions simultaneously (sacrificing the full Stokes polarimetry) would be a significant advantage. This might even be usefully extended to observe four transitions simultaneously with a single polarisation. For methanol masers at 25GHz the same considerations apply as for Water masers.

Status: on-going  (updated 2002 Apr 03)
Work on the integration of the S2-DAS with the MultiBeam correlator is continuing. It is expected that this wider role for the MB correlator will make it unnecessary to upgrade the "Parkes AT correlator", which was an item in earlier development plans. The new 1GHz b.w. pulsar correlator will also enhance spectral line capabilities at Parkes.

Proposed: 1996 May 17?  Funding:  not_funded

Currently the inner 17 meters of the Parkes 64m telescope are solid panels shaped and set to a precision to allow observations at wavelengths as short as 7mm. The upgrade of the focus cabin has added to the additional shadowing of this area. Thus the existing area may be marginal for observations at 7mm. We proposed to study the feasibility of extending the precision surface to a diameter of approximately 21 meters. This would require the replacement of the next row of panels on the surface with higher precision solid panels. The study will include consideration of the additional wind loading, required changes to existing feeds, costs, and comparison with the Mopra dish.

Status: no action  (updated 2001 Feb 19)

## 3. Mopra 22m Telescope

### 3.1. Digital Filter Bank Spectrometer

Project Leader: W. Wilson, Project Scientist: UNSW
Proposed: 2002 Mar 27  Funding:  arc grant to unsw/atnf.

In collaboration with UNSW, a new 8GHz bandwidth Digital Filter Bank Spectrometer will be constructed for the Mopra telescope. The spectrometer will use technology being developed for the MNRF2001 Wideband Compact Array correlator. The specifications are: 2 polarisations, 4 x 2GHz bandwidth 4096 channel filter banks on each polarisation.

Status: on-going  (updated 2002 Oct 31)
Initial design of a digital filter bank spectrometer is in progress. The aim is to produce a proof of concept prototype unit with 256MHz bandwidth. A test installation of this unit is planned at Mopra in mid-2003. Project has been costed, and funding is available.

Project Leader: R.J. Beresford, Project Scientist: J.E. Reynolds
Proposed: 1999 Mar 23  Funding:  not_funded

This is a proposal to create an interferometer between the ATCA and Mopra telescopes, akin to the Parkes-Tidbinbilla Interferometer. An optical fibre link appears feasible, and could produce significant scientific returns. For details and costing, see the Triennium+20% science case.

Status: no action  (updated 2002 Sep 30)
This project, together with the full 7mm system, was the second highest ranked, currently not funded, project coming out of the +20% Triennium funding deliberations by the AT Users Committee (see the ATUC Report from March 1999 ).

There are several interested parties in the region trying to aquire affordable access to fiber.

Project Leader: G. Moorey, Project Scientist: D.L. Jauncey
Proposed: 1996 May 17  Funding:  not_funded

A 7mm receiver at Mopra would play an integral role in Long Baseline Array operation at this frequency, as well a providing a single-dish 7mm facility for study of molecular masers and numerous continuum projects.

Status: no action  (updated 2003 Feb 26)
Project has been costed, but no action has been taken; status pending on long-term ATCA 7mm developments. A number of MMICs for the 7mm band have been designed and tested under the ESP programme.

## 4. Long-Baseline Array

### 4.1. VSOP: VLBI Space Observing Programme

Project Leader: D.L. Jauncey, Project Scientist: D.L. Jauncey
Proposed: 1996 Jul 1?  Funding:  no_data

The ATNF is playing an important role in the programme to place the first dedicated VLBI radiotelescope into Earth orbit. The satellite, designed and constructed by the Japanese Institute of Space and Astronautical Science (ISAS), was launched successfully from Japan on 12 February 1997, with regular observations to commence around May 1997.

The VSOP spacecraft is primarily an imaging mission, with orbital parameters chosen to give good uv-coverage out to about three earth diameters at observing wavelengths of 18cm, 6cm and 1.3cm, representing a significant upward leap in resolution over earth-only VLBI imaging.

While the spacecraft itself is managed by ISAS, the larger mission is a truly international effort, involving coordination of terrestrial VLBI resources, construction of a global network of tracking stations to record the spacecraft VLBI data, and the scheduling of ground radiotelescopes to co-observe with the satellite. The ATNF has participated actively in the planning and execution of these mission elements and has committed significant fractions of observing time on the Compact Array and Mopra telescopes specifically for VLBI co-observation VSOP.

From a technical point of view, co-observations with VSOP pose few special problems for ground radiotelescopes, but there are considerable logistical challenges given the likely observing load. At this stage it is anticipated that current levels of support for VLBI within the ATNF and from the MNRF will be adequate. A H-maser clock at Narrabri is also extremely desirable, since performance at 6cm (5GHz) is significantly degraded by the existing Rubidium oscillator currently in use which is well past its nominal lifetime.

The additional observing load on the LBA to support VSOP observations will probably require purchase of additional S2 S-VHS tapes, above those intended for use in LBA-only observations.

Status: on-going  (updated 2002 Apr 08)

NASA withdrew support for the mission in February this year. This resulted in the mission losing the NASA tracking stations and Green Bank, as well as access to the VLBA and the VLBA correlator. Without the VLBA correlator, the EVN is effectively lost to the mission too. However, the mission is continuing to observe using predominantly S2 recording, and through the Japanese tracking station. While the General Observing program is seriously effected without access to the VLBA and the EVN, it is still possible for Target of Opportunity proposals to be submitted through until 2003 using the presently available resources.

For Mopra, a formal request, with scientific justification, was made by the VSOP mission to the ATNF TAC to continue support for the VSOP Survey Program until Feb 2003. This appears to have been well received, and the VSOP Survey observations, at the rate of 1-2 observations per week, will continue through February 2003, as requested. Negotiations are underway between the ATNF and VSOP for the southern winter mm period, when VSOP observations will be curtailed because of the mm commitments.

VSOP observations of a small number of the highest ranked Key Science Programs have been requested for the ATCA during the coming year. Four have been requested, and the ATCA has agreed to support two of these.

Over the course of the mission to date, some 45 VSOP observations have been supported at Ceduna, 60 at Tidbinbilla, 80 with the ATCA and 190 with Mopra. The Southern Hemisphere has made a major commitment to the VSOP mission, and this support is greatly appreciated by the mission.

## 5. RFI Mitigation

### 5.1. EMC Compliance Facility (Screened Room)

Proposed: 1999 Jan 1  Funding:  triennium?

A major part of the ATNF interference mitigation philosophy involves the quality control of custom-built and commercial equipment from the RFI standpoint. To allow compliance testing of systems destined for observatory use, we anticipate the need to purchase or manufacture a room-sized RF-tight enclosure. The final strategy will be decided as part of a cohesive interference mitigation project but, at this stage, we draw users' attention to the scale of the project and its value in achieving lower levels of self-generated interference at our observatories.

Status: on-going  (updated 2002 Sep 30)

We have been fortunate to acquire two screened rooms which were surplus to requirements at CTIP, Lindfield. One of these rooms will be assembled at Parkes, while the other will be set up at Marsfield as a general-purpose test chamber. The chamber will be useful for measurement, development and EMC quality assurance purposes.

### 5.2. Parkes tower screening

Project Leader: M. Smith, Project Scientist: J.E. Reynolds
Proposed: 1998 Jul 1  Funding:  triennium

The Parkes Radiotelescope, like many other radioastronomy observatories, suffers from radio-frequency interference (RFI). The RFI can be generated locally, through un-intended emissions from the numerous items of equipment at the observatory site, from licensed terrestrial transmitters, which produce harmonics and other out-of-band emissions which pollute the protected radioastronomy observing bands, and from licensed space-borne transmitters, which again, produce harmonics and other out-of-band emissions which fall into the protected radioastronomy bands.

The Parkes RFI mitigation plan is to provide a process for characterising, and when possible, minimising the effects of sources of RFI, on observational data. Through a programme of on-site measurements, screened structures, and utilising the resources of the Australian Communications Authority database of licensed transmitters, progress towards the mitigation plan is coming to fruition.

Status: on-going  (updated 2003 Feb 24)
On-line programs and databases are currently being used to characterise the RFI environment of the observatory, and a purpose built anechoic chamber is currently used to measure the RFI signatures of equipment, when required. A number of the site PCs are now enclosed in purpose built screened cabinets, and a stand alone tower, 1km from the observatory is to be furbished, such that a separate RFI monitoring station can be established, for measuring the RFI environment around the observatory, utilising the soon to be completed IMS.

The 60-foot service tower has completed phase 1, of its upgrade to allow a stand alone tower for the purposes of RFI direction finding and characterisation. The platform, and air-conditioned equipment room are installed on the tower. The Interference Monitoring System (IMS) is about to be installed in the equipment hut, for initial site RFI charaterisation measurements. Phase 2 of the upgrade will commence next financial year, to include the refurbishment of the hut at the top of the tower, to aford a higher vantage point for direction finding antennas. The final phase of the upgrade will involve the connection of the service tower to the main observatory via a optical fiber link, for real time RFI monitoring, again to be completed next financial year

### 5.3. Mobile RF measuring system

Project Leader: M. Smith, Project Scientist: J.E. Reynolds
Proposed: 1997 Jan 1?  Funding:  triennium

The Interference Measuring System (IMS) has precipitated out of the requirement to be able to measure interference signals, which affect radio-astronomy receiver systems. These receiver systems are very sensitive, and main-beam side-lobe coupling of external radio frequency sources, into the radio-astronomy receivers, cause interference. The IMS has to be able to measure these RF sources, which couple into the receiver system. Current techniques for measuring interference signals at the observatories, typically utilize a feed-horn, a set of amplifiers, and a spectrum analyser. With this setup, the noise floor of the measurement system, is typically many orders of magnitude greater than the interference power level, and thus the interference signal is buried in the measurement system noise floor. Reducing the spectrum analyser resolution bandwidth can reduce the noise floor of such a system, however, the resulting configuration constraints resulting from such a setup yields a measurement system incapable of providing useful and timely results.

The IMS moves away from the measurement principles of the spectrum analyser which utilizes swept narrow-band filters across the spectrum, by using the principles of noise measuring radiometers. Radiometers afford the ability to measure the extremely weak signals which appear at the input to such radiometers systems, through the use of integration techniques, coupled with a sampler/correlator backend, for signal processing.

Status: complete  (updated  2003 Feb 24 )

Construction of the Interference Measurement System (IMS) is complete. The IMS will be undergoing field trials, system sensitivity, and calibration measurements from the recently completed service tower platform and equipment hut, on-site at the Parkes Radiotelescope. Hardware used to make the IMS independent of the Parkes Observatory, have now been purchased and integrated into the IMS, specifically a synthesized signal generator to provide an agile Local Oscillator, a power meter for level setting for the correlator, and an integrated phase locked crytsal oscillator, to supply the sampler clock. Equipment to extend the IMS range up to S-Band has been purchased, and is awaiting integration into the IMS system.

## 6. Computing Systems

### 6.1. ATOMS/ACC support

Project Leader: M. Wieringa, Project Scientist: D. McConnell
Proposed: 1995 Jan 1  Funding:  triennium

The current generation of Antenna Control Computers (ACCs) at Narrabri are near the end of their useful life, with replacement parts no longer available. The reliability and maintenance of these systems may become serious problems if the systems are not upgraded soon. There is also currently a processing bottleneck with the ACCs which limits the manner in which the Compact Array can be used. This will be rectified with the upgrade. Work on the ACC replacement is being carried out as part of the ATOMS project.

Status: on-going  (updated 2002 Oct 28)
The new ACCs have been tested in both normal observations and to support the wideband correlator survey observations. These tests were generally succesful, but uncovered a number of problems which are now being addressed. Six new ACCs are now permanently installed in the the antennas and can be brought into operation in less than an hour, should we run out of spare old ACCs.

While we resolve the remaining problems with the new ACC software we will continue using the old ACCs for regular observing, but we expect a switchover (with old ACCs as fallback) before the end of the year if no new problems are found. It must be noted that the pSOS development system continues to give us problems (e.g., lack of proper debug facilities, occasional errors in floating point emulation).

## 7. Strategic Research

### 7.1. SKA

Project Leader: P.J. Hall, Project Scientist: R.P. Norris
Proposed: 1999 Jan 1  Funding:  triennium

Radio astronomy has since the 1940's opened a large field of research from pulsars to highly energetic sources like quasars. With the advent of greater sensitivities at other (higher) frequencies, a deeper insight in the physical properties giving rise to the observed phenomena has become possible.

Understanding the latest results at optical and other frequencies, and the expected wealth of new phenomena expected with the new generation of 8-m telescopes coming on-line, is in some cases only possible with information at lower frequencies. Sensitivities necessary to probe the edge of the universe to answer questions like 'when did the early universe reionise', 'are there discrepancies in relativity theory', 'when did first stars/galaxies form' can only be answered by an instrument at radio wavelengths with a collecting area of about a kilometre square.

SKA specification and development is being undertaken by the ATNF in collaboration with international and Australian partners. In late 1999, CSIRO provided \$1.5M in seed funding to establish a formal SKA development Program. This Program, which runs until mid-2003, has now been defined formally and a number of projects and activities are underway.

Status: on-going  (updated 2003 Feb 26)

In August 2001 the ATNF received news that the MNRF2 bid had been successful. While final divisions have yet to be decided, at least \$18M will be spent on Australian SKA research over the next five years. The main threads of the MNRF submission were

• the construction of two SKA demonstrators,
• the development of important enabling technologies for SKA, and
• the establishment of a supercomputer facility to support astronomy and engineering simulations needed in designing the SKA.

The ATNF and the University of Sydney will undertake the SKA demonstrator work, while Swinburne University of Technology will lead the SKA simulation activities. Enabling technologies will be developed by the ATNF and CTIP, in collaboration with initial industry partners such as CEA Communications and Advanced Powder Technologies.

Good progress has been made on multibeaming antenna prototyping. A prototype 1m lens based on new CSIRO artificial dielectric is due for delivery in mid-2003. Associated with this will be a demonstration feed translator system. We hope to have the prototype available for demonstration at the Geraldton SKA 2003 meeting in July.

The MNRF agreement also calls for work in the phased array area, and a first proposal (PDF, 83k) for a novel 'digital' array, potentially suitable for Parkes, has been developed. This work would be conducted in association with ASTRON and CEA. Under the terms of the MNRF, a decision on which cm-wave multibeaming path (lens or array) to follow through to large-scale demonstrator status is due in mid-2004; the present early development and experimental work is crucial in this process.

Project Leader: M. Storey, Project Scientist: R.D. Ekers
Proposed: 1997 Jul 1?  Funding:  ska

Following the initial interest by the Western Australian government to establish a Radio-quiet Reserve for compatible scientific facilities, including the SKA radio telescope, three other states, South Australia, Queensland and New South Wales have now expressed interest in the project. A Radio-quiet Reserve is an area of land about 50km in diameter protected by legislation and regulation.

The ATNF is participating in an international SKA Working Group on site selection methodology and which will define agreed standards for site selection. Preliminary Proposals for hosting the SKA are due in October 2004.

Status: on-going  (updated 2002 Oct 31)

All participating states are continuing studies to define potential areas for a Radio-quiet Reserve. Western Australia has provisionally set aside two areas in the Murchison (NE of Geraldton), and a very remote area east of Kalgoorlie is being studied. The radio-quietness measurements carried out in March/April 2001 have now been analysed. A site in the Murchison is being considered by the LOFAR consortium as one of three potential sites. South Australia is continuing investigations of a site near Lake Eyre and NSW is continuing studies of areas in the state's north-west. The ATNF assists the states in these studies.

A meeting held on 7 June 2002 resulted in the eastern states (NSW, SA, QLD) agreeing, in principle, to cooperate on site studies. There was also recognition that the other states had to work quickly to advance their site studies to the point that WA site investigations have reached.

As part of Australia's effort in supporting a submission of a Preliminary Proposal for hosting the SKA, the ATNF is developing a high-sensitivity Interference Monitoring System which will determine the ambient noise level of potential sites. An RFI measurement program will form part of an extensive site evaluation program by the states in 2003.

With Bruce Thomas' retirement, Michelle Storey has taken up leadership of the project, for the interim. A new coordinator (advertised position) will be appointed, and Ron Ekers will be advancing the radio-quiet reserve as part of his Federation Fellowship work.

More information:  Strategic Research into the Square Kilometre Array telescope (SKA) and SKA - Square Kilometer Array.
Bruce Thomas' report (Oct 2001).

### 7.3. Single dish software (TCS)

Proposed: 1997 Mar 14  Funding:  triennium?

This project was started to develop a coherent software suite for operating ATNF single dish telescopes, particularly Parkes. It was aimed at providing replacements for the various pieces such as NODDY, SPECTRA etc. This is expected to be an on-going exercise.

Status: on-going  (updated 2002 Oct 31)

The "vaxxination" (migration from VMS) is now complete. Latest major step was to adapt to the new pulsar backends (ATNF wideband correlator and the Caltech/Swinburne/Parkes system). The focus cabin computer (FCC) has switched from pSOS operating system to linux.

### 7.4. Interference excision

Project Leader: M.J. Kesteven, Project Scientist: R.J. Sault
Proposed: 1995 Jan 1  Funding:  mnrf1997, ska

Terrestrial and satellite interference, both broad-band and narrow-band, is an increasing problem at all wavelengths. It is especially troublesome at lower frequencies for both spectral-line (e.g. 1612MHz OH) and pulsar observations. It is most serious for single-dish observations, but also a concern for interferometric arrays.

Protection through frequency allocation regulations, though essential, is not by itself adequate to protect radio astronomy observations. Techniques to avoid or suppress interference, both real-time and off-line, need to be developed beyond their present rather elementary level. The interference mitigation project will be affiliated with the new SKA Programme, with ATNF efforts being centred on sub-projects which complement international efforts. These include studies in robust receiver design, aperture and focal plane post-correlation techniques, and software radio telescope development (allowing experiments on real data using beam null steering and many other signal processing approaches).

An immediate goal of the project is to develop interference mitigation scheme exploiting the "post-correlation" technique and specialised hardware. An L-band feedhorn has been adapted to provide the reference antenna used in this scheme, and low-noise room temperature amplifiers have been purchased.

Status: on-going  (updated 2001 oct 2)

Recent experiments at Narrabri have included a successful 12-hour run at 1503 MHz, countering the pay-TV on Mt. Dowe. A test at 1610 MHz (countering the Glonass constellation) is at the data analysis stage, and looks promising. The trials so far have been narrow band (4 and 8 MHz); wide-band trials at S-band are under consideration.

During the past 6 months some datasets have been presented for post-correlation removal, not all of which were amenable to the technique. There will be further hardware trials, but no details are defined as yet.

This development was supported by MNRF funding. It is now under the SKA arena. Reports and backround can be accessed via the SKA site.

### 7.5. Test equipment

Proposed: 1995 Jan 1  Funding:  mnrf1997?

The acquisition of modern high-frequency test equipment is an essential corequisite for the development of mm-wave systems.

Status: on-going  (updated 2003 Feb 14)
A 50GHz frequency synthesiser has been bought.

## 8. External Contracts

Project Leader: W. Wilson, Project Scientist: W. Brouw, Project Engineer: R. Gough
Proposed: 2002 May 1  Funding:  contract

This project is a research and development effort aimed at producing receiver arrays that would be installed on radio telescopes. At the heart of the project is the design of MMICs for cryogenic application at frequencies of 20-40~GHz, and for non-cryogenic phased arrays in the 2-5 GHz band. The project is focussed on three innovative array configurations:

1. Horn arrays for large-area continuum surveys near 30 GHz. The effects of receiver gain changes and variations in atmospheric attenuation will be reduced by signal comparison strategies involving switching the signal between independent receivers and closely-spaced horns. The deliverables are an 8-horn prototype array (to be tested on the Torun radio telescope) and a feasibility study for a 100-horn continuum array.
2. Horn arrays for spectroscopy in the band 21-26 GHz a heterodyne design will be adopted with a down-converter integrated into each channel; this enables the spectrum of the signal to be obtained and the operating frequency to be varied. The deliverables are a 5-element prototype array (to be tested on the Medicina or Noto radio telescopes) and a feasibility study for a 50-horn spectroscopic array at 40-50 GHz.
3. Actively phased arrays at 2-5 GHz. In this concept the receivers are interconnected so that multiple beams can be synthesised and steered electronically by phasing; the aim is to improve the efficiency of individual telescopes and to open up the widest possible field-of-view. The deliverables are a 16-element 2-beam prototype array to work in the frequency range 2.5 to 5 GHz (to be tested on a Westerbork telescope and on an ATNF-designed Luneberg lens) and a feasibility study for a 16-beam phased-array in the band around 5 GHz, generically suitable for any large European telescope.

The project also involves the design of flexible data analysis software tools for the acquisition and analysis of data from horn arrays. The software will be written within the international astronomical standard AIPS++ environment. Since the astronomical aim of this RTD programme is the making of much larger radio surveys we are conscious of the need to link this work in with both National and Europe-wide initiatives for data archiving and Virtual Observatories.

Status: on-going  (updated 2003 Feb 26)

The partners in the project are

• University of Manchester, Jodrell Bank Observatory (UK)
• Consiglio Nazionale delle Richerche, Instituto di Radioastronomia (Italy)
• Astronomisch Onderzoek in Nederland (ASTRON) (Holland)
• Nicolaus Copernicus University, Torun Centre for Astronomy (Poland)
• CSIRO Australia Telescope National Facility

Plans are for CSIRO and the University of Manchester to design the circuits, and CSIRO to submit the designs for fabrication, and perform on-wafer testing. Receivers utilising the MMICs would be installed on the Torun (Poland) and Medicina or Noto (Italy) radio telescopes.

InP MMIC designs by ATNF, Jodrell Bank and ASTRON were submitted for fabrication in February 2003.

### 8.2. Arecibo 7-beam 21cm multibeam

Proposed: 2001 Feb 1  Funding:  contract

The ATNF is discussing designs and specifications with Arecibo Observatory for a 7-element multibeam feed for 21cm observations.

Status: on-going  (updated 2003 Feb 26)
The feed design has been completed by Trevor Bird (CTIP) and quotes for manufacture maintained. The final receiver and dewar designs have been signed off. The installation date is set for April 2004.

We have started manufacture and have let contracts to outside firms for manufacture of some of the many metal components. The dewar cylindrical section and end plates are the important ones at this stage and we look to test for a good vacuum once they are completed.

An Ortho Mode Transducer prototype, based on the Parkes model but with variations to allow greater bandwidth, has been made and refined till a suitable final design was attained. The final 7 are under construction. Trevor Bird's group tested a prototype feed horn and the results agreed closely with their modelling so the manufacture of the rest can proceed.

Machined bodies for the amplifiers have been received. Once these have been plated, the amplifiers will be constructed. A contract has been let for the supply of the feed rotation system. This is a much simpler design than Parkes and some components for the system are in house.

### 8.3. AMIBA collaboration

Project Leader: W. Wilson, Project Scientist: M.J. Kesteven
Proposed: 1999 Sep 23  Funding:  contract

A Memorandum of Understanding between ATNF and Academia Sinica Taiwan (ASIAA) has been agreed upon. Senior ATNF engineers and scientists will consult in the design of a new CMB telescope called AMiBA. The telescope will be a nineteen element interferometer with full polarisation capability operating at a frequency of 95GHz. Major goals are measurements of the CMB polarisation and investigations of the Sunyaev-Zeldovich Effect.

Status: on-going  (updated 2003 Feb 25)
ATNF is providing assistance in the following areas:

• array configuration studies
• determination of atmospheric effects at chosen sites
• overall system specification