African VLBI Network

African VLBI Network
Name	African VLBI Network
Organization	South African Radio Astronomy Observatory, Hartebeesthoek Radio Astronomy Observatory, University of Nairobi, Ghana Space Science and Technology Institute
Location	South Africa, Kenya, Ghana, Mauritius, Madagascar, Zambia, Namibia
Wavelength	Radio, Very-long-baseline interferometry

African VLBI Network. The African VLBI Network is a collaborative astronomical project establishing a continent-wide array of radio telescopes for high-resolution observations. It is a key component of the global Very Long Baseline Interferometry system, enhancing the Event Horizon Telescope's imaging capabilities. The network leverages existing infrastructure like the Hartebeesthoek Radio Astronomy Observatory and is central to the Square Kilometre Array project's precursor science.

Overview

The initiative emerged from the need to improve uv-coverage for global VLBI arrays and to foster radio astronomy development across the African continent. It is intrinsically linked to major international projects, including the Square Kilometre Array, whose core will be located in the Karoo region of South Africa. The network's formation was significantly advanced through partnerships with the European VLBI Network and support from organizations like the African Union. Its development represents a strategic effort to build scientific capacity and infrastructure within multiple African countries.

Member telescopes and locations

The network incorporates both converted telecommunications antennas and newly built instruments across several nations. Key stations include the existing 26-meter dish at the Hartebeesthoek Radio Astronomy Observatory in South Africa and the 32-meter telescope at the Mauritius Radio Telescope site. In Ghana, the former Kutunse Satellite Communication Station has been refurbished for astronomical use. Other participating nations hosting or planning stations include Kenya, Madagascar, Zambia, and Namibia, creating baselines exceeding thousands of kilometers.

Scientific objectives and research

Primary research goals include imaging supermassive black holes, such as Sagittarius A* at the center of the Milky Way, in collaboration with the Event Horizon Telescope. The network will study maser emissions in star-forming regions and the detailed structures of distant active galactic nuclei. It also contributes to astrometry and geodesy, providing precise measurements of Earth's rotation and tectonic plate motions. These observations are vital for testing theories of general relativity and understanding galaxy evolution.

Technical specifications and capabilities

The array operates across key radio frequency bands, including L band, C band, and K band, compatible with global VLBI standards. Telescopes like the one at Hartebeesthoek Radio Astronomy Observatory are equipped with state-of-the-art hydrogen maser frequency standards and Mark 6 recorder systems for data capture. The long baselines between stations, such as from South Africa to Ghana, provide angular resolution capable of discerning details at the micro-arcsecond level. Data is correlated at facilities like the Joint Institute for VLBI ERIC in Europe.

Collaboration and governance

The network operates under a framework established by the South African Radio Astronomy Observatory, which serves as the lead technical partner. Governance involves a consortium of national agencies, including the Ghana Space Science and Technology Institute and the University of Nairobi. Funding and support are provided through international agreements with the European Commission and scientific bodies like the International Astronomical Union. Training and development programs are often conducted in partnership with institutions such as the National Radio Astronomy Observatory in the United States.

Future developments and expansion

Future plans include integrating new stations in Nigeria and Botswana to further improve the array's imaging fidelity. A major goal is the construction of the African Millimeter Telescope in Namibia, which would be a dedicated instrument for higher-frequency observations. The network's capabilities are expected to be fully realized as a critical precursor instrument for the Square Kilometre Array Phase 1. Continued expansion is supported by the Pan-African University and initiatives like the African Initiative for Planetary and Space Science.

Category:Radio telescopes Category:Astronomical observatories in Africa Category:Very-long-baseline interferometry