Intensifying the Intensives with the VLBA

The U.S. Naval Observatory has, since late 2011, been observing a UT1-UTC Intensive series using the Very Long Baseline Array (VLBA). The primary baseline for these sessions is Mauna Kea - Pie Town (MkPt), using Los Alamos - St. Croix (LaSc) as secondary stations. The session observation times are offset by eight to 16 hours from the IVS Intensives. The VLBA Intensives series are observed at the standard S/X bands. In addition to the daily single baseline VLBA Intensives, VLBA fortnightly sessions using up to four VLBA antennas are observed to characterize the additional baselines. The stations that participate in the fortnightlies are Mauna Kea (Mk), Pie Town (Pt), Los Alamos (La), and St. Croix (Sc). During the period when Sc was offline due to Hurricane Maria damage, a tertiary Intensive was observed using Hancock - Owens Valley (HnOv). Hn and Ov were added to the fortnightlies. We present results of these UT1-UTC series to date and discuss future observing. One issue with the current observations is that the S-band can often be affected by RFI, which usually leads to dropped channels and increased noise in the data. To address the RFI in S-band, test observations are being done to characterize the performance of the VLBA using its more sensitive C-band. Potential future goals include extending the Intensives using three-station baselines to maximize the east-west array.