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October 20, 2018


Global VLBI Solution 2001d
October 2001


Presented here is the U.S. Naval Observatory's 2001d global solution.
The Batch SOLVE solution used all available multibaseline VLBI observations
at 8.4 GHz (Xband) and 2.2 GHz (Sband) from 3 August, 1979 through 09 October,
2001. This included a total of 2895 diurnal sessions
and 2,844,574 measurements of group delay. The
Batch control file
2001d.cnt
was used to generated this solution with an output spool file
2001d.spl.gz.
Plotted and tabulated below are the global and session RMS values for
the solution.
Earth Orientation Parameters
The Earth Orientation parameters: X and Y pole positions and rates,
UT1 angle and rate, and daily offsets in the nutation in longitude and obliquity
were estimated for each session separately. The data were filtered
such that sessions with EOP formal errors greater than 30 nanorad or with
correlations greater than 0.97 were removed. This resulted in the removal
of 145
sessions
from the EOP data. Plotted and tabulated below are these data.
Pole Position X vs. Y: Jan. 1993 to
Sept. 2001 (
postscript
,
pdf
) 

Full EOP time series: X pole, Ypole, UT angle (
postscript
,
pdf
) 

Full Nutation offset time series: Longitude and Obliquity
(
postscript
,
pdf
) 

Tabulated data.
Station and Source Positions
Positions of 527 sources were estimated as global parameters. Sources which
participated in 2 or more sessions, had 40 or more good observations, and
normalized residual delays less than 1.3 in the CRF2001a solution qualified
for the list of global sources. Positions for an additional 140 source
were estimated for each session independently as local parameters. Positions
of 129 stations and velocities for 118 of those stations were estimated
as global parameters.
Tabulated data.
Comparisons
Shown below is a comparison of the USNO 2001d solution with the
IERS C04 time series. A weighted leastsquares fit to the
difference plots and the weighted rms are shown on each plot.
Shown below is a comparison of the USNO 2001d solution with the
GSFC 2002a solution. A weighted leastsquares fit to the difference
plots and the weighted rms are shown on each plot.
This is an Official U.S. Navy Web Site

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