Speaker
Description
The Africa Millimetre Telescope (AMT), planned for construction in Namibia, will expand Africa’s contribution to millimetre very-long-baseline interferometry (VLBI) and the Event Horizon Telescope (EHT), supporting future EHT and multi-wavelength studies of supermassive black holes, accretion flows, and relativistic jets. Its ability to participate effectively in EHT observations will depend on both the sensitivity of the telescope and the stability of the atmosphere above the observing site. In this study, we assess the expected fringe detectability of the AMT with ALMA and NOEMA at 230 GHz for observations of Sgr A and M87. The sensitivity of the AMT is estimated using atmospheric and site conditions measured in situ at the candidate sites, together with models of atmospheric opacity, system temperature, and antenna performance. These estimates are combined with ALMA and NOEMA SEFDs derived from EHT system-temperature and gain calibration data to determine the expected signal-to-noise ratio of the corresponding VLBI baselines, providing a direct measure of the detectability and reliability of the correlated fringes. Atmospheric coherence times at the AMT candidate sites are estimated using phase-monitoring stations developed at Radboud University. To calibrate these instruments, measurements from a Radboud phase monitor installed at the IRAM Plateau de Bure site are compared with those from the established IRAM phase-monitoring system at the same site. The resulting relationship was then be applied to the phase-monitoring stations operating at the candidate AMT sites in Namibia. By combining station sensitivity, atmospheric coherence time, source visibility, and expected source flux, we aim to determine the periods during which useful fringes are most likely to be detected.