The AuScope VLBI Array

1. The AuScope VLBI Array John Dickey University of Tasmania 9 March 2007

2. This is part of a project for geodetic research funded under NCRIS 5.13: Structure and Evolution of the Australian Continent Chief Investigator: Michael Etheridge Project Scientist: Kurt Lambeck / Paul Tregonning Project Manager: Gary Johnston Universities involved: ANU, Curtin, Macquarie, Monash, Swinburne, Adelaide, Melbourne, Queensland, Sydney, Tasmania, WA Institutions: CSIRO, Geoscience Australia, State Geo. Surv. Queensland, WA, NSW, NT, Vict., ACT, SA, Tas, …, NASA

3. seismic and MT imaging … budget $8M + $5M virtual core library … 3 + 8 geochemical analysis … 3 + 39 geospatial framework … 17 + 48 VLBI + SLR + GNSS + Gravity simulator … 8 + 11 grid … 6 + 3

4. The VLBI portion will fund three new 12m diameter telescopes, with uncooled 11cm and 3cm receivers, maser time standards, LO’s, IF’s, and disk based recorders at two new sites (plus Hobart), and a dedicated correlator facility (Swinburne). hardware budget 4+ M$ The objective is to tie Australian geodesy into the International Geospatial Reference Frame, which is tied to the International Celestial Reference Frame. To do this we must improve the ICRF in the southern sky.

5. UTas is a member of the International VLBI Service The IVS is a collaboration of 29 radio telescopes that keep track of the Earth Orientation Parameters, numbers that tell how the earth is rotating and which way the axis is pointing. These are used to calibrate GPS and all other location-finding equipment.

6. Stations of the International VLBI Service

7. Motion of the earth’s polar axis (north) measured on the sky, relative to extragalactic radio sources. 1 mas ~ 10-9 of a circle (one 4-millionth of a degree) ~ 3 cm on the earth’s surface

9. get this data from http://hpiers.obspm.fr/eop-pc/index.html The length of a day varies by a few hundred micro-seconds each day. This is partly predictable, partly unpredictable.

11. The AUScope array will be hugely significant for southern hemisphere geodesy. It will also be an immense improvement to our astronomical VLBI capability…

12. U Tas Radio Telescopes are the Backbone of Very Long Baseline Interferometry in Australia

13. The Four Element LBA, with • Parkes • Narrabri (1 elt) • Mopra • Tidbinbilla 128 mas at 5 GHz FWHM 16 mas

14. U Tas Radio Telescopes are the Backbone of Very Long Baseline Interferometry in Australia

15. The Six Element LBA, with • Parkes • Narrabri (1 elt) • Mopra • Tidbinbilla • Hobart • Ceduna 128 mas at 5 GHz FWHM 8 mas FWHM 8 mas

16. Katherine Yarragadee

17. The Eight Element LBA, with • Parkes • Narrabri (1 elt) • Mopra • Tidbinbilla • Hobart • Ceduna • Yarragadee • Katherine 128 mas at 5 GHz FWHM 5 mas

18. Observing a synthetic source at  = -88o with UVCON: peak flux ratio = 0.37 total flux ratio = 0.034 50 mas at 5 GHz as seen with the new array as seen without the UTas telescopes as seen with the 6 element array

19. Things are not so nice at declination -45o … 4 element array 6 element array 8 element array

20. Recent Progress: In addition to the AuScope array, New Zealand will construct one 12m telescope to be dedicated to VLBI for geodesy and astronomy. Principal Investigator: Sergei Gulyaev Auckland University of Technology Congratulations, Sergei !

23. Current state of project: • defining specifications for antennas and receivers • prototype correlator at Swinburne in progress • site selection in NT • Urgently needed: • co-funding to allow astronomical considerations to be included in receiver and antenna specs • VLBI_2010 specifications determined • (slew rate, upper frequency limit)

24. Conclusion: The AuScope array will operate ~50% time for geodesy. The rest of the time will be available for other research, provided extra operations and capital costs are covered This will be a huge improvement in the LBA capabilities, particularly for bright sources and for astrometry.