1. 03/000 New geodetic VLBI dish in WA Australian Government Geoscience Australia

2. Existing VLBI facilities Geoscience Australia 07 July 2005 Hobart (26 m) ~ 50 sessions/y - UTAS Parkes (64 m) ~ 1-3 sessions/y - ATNF Tidbinbilla (34 m) ~ 2-3 sessions/y - NASA

3. Problems Geoscience Australia 07 July 2005 All dishes are operated by external agencies No link between VLBI and SLR provided Unsufficient geographic position High elevation limits (Parkes): correlation between height and wet delay General weakness of the ICRF in the southern hemisphere – uncertainty in VLBI and GPS heights for Hobart ~ 1 cm! Design deterioration (Hobart) – low slewing speed, hydrogen maser instability, shape deformations, etc.

4. Key problem – slewing speed Geoscience Australia 07 July 2005 Mount [deg/min] [deg/min] ------------------------------------------------------- Hobart XYEW 40 20 HartRAO HADC 24 22 Kokee AZEL 120 120 -------------------------------------------------------

5. Simulation Geoscience Australia 07 July 2005 Goddard Space Flight Center (NASA) Typical network: 6 dishes in Northern hemisphere + addition

6. Simulation Geoscience Australia 07 July 2005

7. Simulation results Geoscience Australia 07 July 2005 Model sXp sYp sUT1 sNut1 sNut2 chi-sq Num (mas) (mas) (ms) (mas) (mas) ____________________________________________________________________ 6 st 0.118 0.098 0.0041 0.233 0.082 2.02 3290 6 st + Hartrao 0.101 0.061 0.0042 0.168 0.060 1.65 3179 46 deg/min 6 st + Hobart 0.081 0.069 0.0034 0.156 0.061 1.66 3442 60 6 st + Yarra 0.048 0.038 0.0027 0.112 0.047 1.65 4289 240 6 st + Y&Hart 0.045 0.031 0.0025 0.102 0.041 1.63 4494 6 st + Y&Hob 0.044 0.036 0.0026 0.101 0.043 1.59 4571

8. Solution Geoscience Australia 07 July 2005 New VLBI site in WA (Yarragadee) Next generation radiotelescope to support remote unmanned real time VLBI operation Diameter ~20-25 meter - Cost: 21-meter dish was ~3.1 Mill USD in prices of 2001 (5 Mill AUD in 2005??) Operational costs ~300.000 AUD per year (can be shared with ATNF): 3 staff + equipment/service OR diameter ~10-12 meter – less expansive

9. Goal Geoscience Australia 07 July 2005 Yarragadee (20-25m) ~ 100-150 sessions/y - GA Hobart (26 m) ~ 12 sessions/y - UTAS Parkes (64 m) ~ 1-3 sessions/y - ATNF Tidbinbilla (34 m) ~ 2-3 sessions/y - NASA Hobart (26 m) ~ 50 sessions/y - UTAS Parkes (64 m) ~ 1-3 sessions/y - ATNF Tidbinbilla (34 m) ~ 2-3 sessions/y - NASA 2005 2010

10. Advantages Geoscience Australia 07 July 2005 Operated by GA - more flexibility in scheduling Fast slew – more data, better precision Link between VLBI and SLR, GPS - ITRF Better geographic position Better resolution in height and wet delay - ITRF Strength on the ICRF - ICRF, ITRF Measurement of the intracontinental deformations Near-real time monitoring (e-VLBI) - timeliness Collaboration with astronomers - stimulation of new joint research and programs Leading role for VLBI in the southern hemisphere

11. Outcome in 5 years Geoscience Australia 07 July 2005 ICRF – the number of reference sources in Southern hemisphere (factor by 2-3); ICRF – precision (factor by 4-5); ITRF – consistent multitechnique positions for all Australia VLBI sites on accuracy level of 1-2 mm; Check of the intracontinental deformations; Consistent multitechnique EOP; Learning of seasonal deformations in region; Tracing of troposphere and ionosphere; In case of strong earthquake in WA – monitoring of post- and co-seismic deformations

12. Conclusion Geoscience Australia 07 July 2005 Giant step forward in both directions basic science; public service

13. ICRF defining sources Geoscience Australia 07 July 2005