2:30 PM - 2:45 PM
[G07-5-04] Strategies to improve precision, accuracy, and latency of current and future VLBI Intensive sessions
The International VLBI Service for Geodesy and Astrometry (IVS) observing
programs currently include 1-hour long VLBI sessions normally observed on
one (IVS-INT1, IVS-INT2) or three baselines (IVS-INT3). These sessions are
known as the Intensive (INT) sessions and their purpose is to provide daily
UT1-UTC estimates. However, the short observation duration, the limited number
of participating telescopes, and the timeliness requirements make operation and
analysis of the INTs a challenging task. We carried out different studies that
try to help solving some of the drawbacks of these single-baseline VLBI sessions.
In doing so, various analysis strategies and the impact of auxiliary and
a priori data were evaluated by re-analysing more than one decade of Intensive
sessions observed on the Kokee-Wettzell baseline in fully automated and consistent
manner. We find that the largest variability in the obtained UT1-UTC
accuracy is related to the availability of high-quality a priori Earth Orientation
Parameters. Concerning operational INT processing, one currently faces the
problem that the observed VLBI group delays contain ambiguities which need
to be resolved. This is usually performed in a semi-automated mode. Therefore,
we implemented a fully automated robust ambiguity estimation method based
on the L1-norm, which increased the successfully resolved sessions by at least
5 %. Another question which we addressed is related to the upcoming VGOS
networks and the way how those can deliver ultra-rapid UTC-UTC products.
Based on current INT networks and through extensive simulations we investigated
optimal locations for tag-along stations which enable flexible scheduling of
three-station network sessions which can provide UT1-UTC with high accuracy.
The results from our investigations are important for the transition from the
current VLBI to operational VGOS and pave the way for future high quality
UT1-UTC products.
programs currently include 1-hour long VLBI sessions normally observed on
one (IVS-INT1, IVS-INT2) or three baselines (IVS-INT3). These sessions are
known as the Intensive (INT) sessions and their purpose is to provide daily
UT1-UTC estimates. However, the short observation duration, the limited number
of participating telescopes, and the timeliness requirements make operation and
analysis of the INTs a challenging task. We carried out different studies that
try to help solving some of the drawbacks of these single-baseline VLBI sessions.
In doing so, various analysis strategies and the impact of auxiliary and
a priori data were evaluated by re-analysing more than one decade of Intensive
sessions observed on the Kokee-Wettzell baseline in fully automated and consistent
manner. We find that the largest variability in the obtained UT1-UTC
accuracy is related to the availability of high-quality a priori Earth Orientation
Parameters. Concerning operational INT processing, one currently faces the
problem that the observed VLBI group delays contain ambiguities which need
to be resolved. This is usually performed in a semi-automated mode. Therefore,
we implemented a fully automated robust ambiguity estimation method based
on the L1-norm, which increased the successfully resolved sessions by at least
5 %. Another question which we addressed is related to the upcoming VGOS
networks and the way how those can deliver ultra-rapid UTC-UTC products.
Based on current INT networks and through extensive simulations we investigated
optimal locations for tag-along stations which enable flexible scheduling of
three-station network sessions which can provide UT1-UTC with high accuracy.
The results from our investigations are important for the transition from the
current VLBI to operational VGOS and pave the way for future high quality
UT1-UTC products.