VLBI in Africa Michael Bietenholz Hartebeesthoek Radio Observatory

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

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

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: 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

HartRAO – MeerKAT Baseline ~900 km

J. Horrell, S. Ratcliffe, L. Schwardt

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”

Status of VLBI in Africa: SKA South Africa

Re-use of Satellite Ground Stations for Radio Astronomy There are a considerable number of satellite ground stations in Africa Fully steerable 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

Satellite Earth Stations in Africa Google Earth

Fibre Connections to Africa

Estimated Conversion Costs Upgrade to angle encoders etc$140 K Uncooled, dual polarization receivers & feed horns; C, X and K bands $300 K VLBI phase calibration, LO & IF systems$180 K Backends: VLBI DBBC + MkV + digital multi- channel (e.g., Roach) $280 K Time and Freq. standard (H maser)$240 K Other costs (test equipment, telescope control system, SCADA) $200 K Commissioning team: 3 engineers & 3 technicians * 1 year $400 K Total$1740 K Data: M. Gaylard, HartRAO

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

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

uv-Coverage: with HartRAO, MeerKAT + EVN

uv-Coverage: adding 4  Africa Array

uv-Coverage: with 4  Africa Array

uv-Coverage: adding 4  more Africa Array

uv-Coverage: HartRAO, MeerKAT + LBA

uv-Coverage: adding 4  Africa Array

uv-Coverage: adding 4  more Africa Array

Satellite Earth Stations in Africa Google Earth