VLBI in Africa

1. VLBI in Africa Michael Bietenholz Hartebeesthoek Radio Observatory

2. Current Status of VLBI in Africa: HartRAO Picture: Thomas Abbott

3. Current Status of VLBI in Africa: HartRAO • HartRAO 26-m dish is fully operational again – bearing has been replaced • Regularly taking part in VLBI sessions with EVN and LBA (1.7 - 22 GHz) • Monthly e-VLBI sessions with EVN at 1 Gbps • XDM, a 15-m composite dish, will take over some geodetic observations Picture: Thomas Abbott

4. Current Status of VLBI in Africa: MeerKAT

5. Current Status of VLBI in Africa: MeerKAT • KAT-7, engineering prototype for MeerKAT. All 7 dishes operating with uncooled receivers, cryogenic receivers being installed • MeerKAT will have • 64 dishes, ~13 m diameter, • total collecting area equivalent to ~100 m diameter: most sensitive radio telescope in the Southern hemisphere • 70% of dishes within a 1-km core, remainder out to ~10 km • Frequencies: 0.5-2 GHz and 8-14 GHz • 1 → 2 → 4 GHz instantaneous bandwidths • First VLBI fringes have been obtained between HartRAO and KAT-7: ~900 km , 3C 273, 1.7 GHz • VLBI observations hopefully by the end of 2011

6. HartRAO – MeerKAT Baseline ~900 km

7. J. Horrell, S. Ratcliffe, L. Schwardt

8. VLBI with MeerKAT TAC response: “We are convinced that there is a strong case for MeerKAT to pursue VLBI observations … We will ensure that in due time, MeerKAT becomes affiliated to international VLBI networks in line with time allocation, scheduling and time commitments to these networks”

9. Status of VLBI in Africa: SKA South Africa

10. Re-use of Satellite Ground Stations for Radio Astronomy • There are a considerable number of satellite ground stations in Africa • Fully steerable 20 - 32 m dishes • Surfaces accurate enough for use at least 10 GHz • These stations are rapidly becoming redundant due to the proliferation of undersea optical fibre links, which have much higher bandwidth • There is therefore a possibility to re-use some of these stations for radio astronomy, particularly for VLBI

11. Satellite Earth Stations in Africa Google Earth

12. Fibre Connections to Africa

13. Estimated Conversion Costs Data: M. Gaylard, HartRAO

14. Operations Cost • Including 2 on-site operation technician/scientists, 1 on-site maintenance technician, 2 off-site scientists • Power, water, disk-pack shipping costs, internet and security • $310 K per year Data: M. Gaylard, HartRAO

15. Status of Conversions and New Antennas • A dish is to be constructed in Mozambique (~13-m) in cooperation with SKA South Africa • Negotiations are underway for HartRAO to use one (or more) of the 32-m redundant dishes at the nearby Telkom site for radio astronomy • A 25-m dish is also planned in Nsukka, Nigeria in collaboration with NIAOT from China • There is in-principle approval from the minister of science in South Africa to develop the African VLBI network, although co-funding from the individual nations is required

16. uv-Coverage: with HartRAO, MeerKAT + EVN

17. uv-Coverage: adding 4 Africa Array

18. uv-Coverage: with 4 Africa Array

19. uv-Coverage: adding 4 more Africa Array

20. uv-Coverage: HartRAO, MeerKAT + LBA

21. uv-Coverage: adding 4 Africa Array

22. uv-Coverage: adding 4 more Africa Array

23. Satellite Earth Stations in Africa Google Earth