A Characterization of the ALMA Phasing System at 345 GHz

G. B. Crew;C. Goddi;L. D. Matthews;H. Rottmann;A. Saez;I. Mart??-Vidal

2023-01-01

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Abstract

The development of the Atacama Large Millimeter/submillimeter Array (ALMA) phasing system (APS) has allowed ALMA to function as an extraordinarily sensitive station for very long baseline interferometry (VLBI) at frequencies of up to 230 GHz (λ ≈ 1.3 mm). Efforts are now underway to extend the use of the APS to 345 GHz (λ ≈ 0.87 mm). Here we report a characterization of APS performance at 345 GHz based on a series of tests carried out between 2015 and 2021, including a successful global VLBI test campaign conducted in 2018 October in collaboration with the Event Horizon Telescope.