Monitoring UT1 using VLBI and GPS estimates

D. Gambis, C. Bizouard and O. Becker

SYRTE, Observatoire de Paris, France

Oral presentation  

The objective of the presentation is to describe the improvements performed at the IERS EOP Product Center to derive an optimal combined series of UT1 based on results obtained by the different VLBI analysis centres. VLBI, as the only technique referring to a non rotating celestial reference frame is the main contributor of UT1 available through the standard and intensive EOP series. Still, LOD estimates derived from the processing GPS observations can be used and combined with VLBI estimates to bring valuable high frequency information. These data based on GPS LOD are in addition essential to ensure a regular daily UT1 determination when VLBI data are missing.