VGOS VLBI Intensives Between macgo12m and wettz13s for the Rapid Determination of UT1-UTC

In this work, we present a status update and preliminary results of the designated research and development VLBI Intensive program VGOS-INT-S, observed between macgo12m and wettz13s for the rapid determination of the Earth’s phase of rotation, expressed via UT1-UTC. Since 2021, 27 Intensive sessions have been observed successfully utilizing a special observation strategy alternating between high- and low-elevation scans for improved determination of delays caused by the neutral atmosphere. Between the end of January and mid of March 2022, VGOS-INT-S was among the most accurate Intensive programs. During this time, eight sessions were observed with an average formal error \(\sigma _{\text{UT1-UTC}}\) of 3.1 µs and a bias w.r.t. IERS C04 of 1.1 µs. Later, the session performance decreased due to multiple technical difficulties.