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====== Global VLBI Alliance (GVA) ======

A Global VLBI Alliance (GVA) to facilitate the flow of information between VLBI networks, including sharing strategies, technical developments for compatibility, logistics, operations, and user support. 

===== MISSION AND SCOPE =====

By its very nature, VLBI has always depended on international collaborations. These have led to the formation of several formal VLBI networks, which in turn regularly form combined arrays. “Global VLBI” is the term often used for the coordinated observations of the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA). In the past, the “Global VLBI Working Group” (GVWG) worked as an umbrella for the space VLBI and ground VLBI network collaboration (VSOP), organizing the logistics (time allocation of ground network resources was agreed in the GVWG) and technical compatibility. Nowadays, as several independent VLBI networks and instruments exist, it becomes timely to recover that spirit, by the establishment of a **Global VLBI Alliance (GVA)**.
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The GVA will facilitate the flow of information between VLBI networks, including sharing strategies, technical developments for compatibility, logistics, operations, and user support. Possibly it will also promote, propose and coordinate common observational campaigns with these existing networks. All these topics have their own characteristics, and appropriate procedures to address them will have to be established. Moreover, with the advent of the Square Kilometer Array (SKA) and its precursors, such global coordination of the various networks and their participating telescopes will be required. The Next Generation Very Large Array (ngVLA) may also collaborate with a global VLBI array. In such scenario, the GVA will serve as contact point and framework of collaboration of the VLBI networks and these other facilities. Additionally, it can encourage and support new VLBI activities (like the African VLBI Network - AVN, Iniciativa VLBI IberoAmericana - IVIA, developments in southeast Asian countries, etc.). The GVA will also facilitate that adequate information is provided to the users. For this, a unique common portal would explain the characteristics of the different networks, and the options for users to access them or in combination.

===== PROMOTORS =====

- European VLBI Network (EVN) [[http://www.evlbi.org/]] \\
- East Asia VLBI Network (EAVN) [[https://radio.kasi.re.kr/eavn/]] \\
- NRAO Very Long Baseline Array (VLBA) [[https://science.nrao.edu/facilities/vlba]] \\
- Australian Long Baseline Array (LBA) [[https://www.atnf.csiro.au/vlbi/overview/index.html]] \\
- Global Millimeter VLBI Array (GMVA, observer) [[https://www3.mpifr-bonn.mpg.de/div/vlbi/globalmm/]]


===== GVA STRUCTURE =====

The GVA is not an organization, but it is organized in several Forum/teams or discussion groups:

- GVA Director´s Forum (GVAD): VLBI network directors or representatives (2 per network) to discuss any aspect of the global cooperation. \\
- Science Forum (GVAS): evaluates and fosters the unique and complementary contribution of VLBI to astrophysical research. Members are active scientists, not necessarily linked to any of the VLBI networks in the GVA.\\
- Technical R&D Forum (GVAT): discusses opportunities and coordinates the development of new instrumentation or procedures.\\
- Operations and Logistics Team (GVAO): facilitates and coordinates observations scheduled with several VLBI networks, or with participation of third-party instruments (e.g. multiwavelength/multimessenger).\\
- Communication and outreach Team (GVAC): coordinates activities and tools to increase the scientific and societal impact of VLBI.

The GVAS, GVAT, GVAO and GVAC, all report to the GVAD.



===== Formalisation as a Working Group in IAU Commission B4 =====

- [[https://www.iau.org/science/scientific_bodies/working_groups/324/|IAU B4 WG "Global VLBI Alliance"]]


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